Terms of Service

These Terms of Service (the "Terms") are a legally binding agreement between you ("you" or "your") and Thornwick Studios Limited, a private limited company registered in England and Wales with company number 16682779 (the "Company", "we", "us" or "our"). They govern your access to and use of Prosa, the browser application at write.prosa.so and the services behind it (the "Service").

The Terms have three parts: (i) the Core Terms, which apply to everyone; (ii) jurisdiction-specific addenda, which add to or modify the Core Terms for people in particular places; and (iii) a model cancellation form. If a Core Term and an applicable addendum conflict, the addendum prevails to the extent of the conflict.

The Service asks you to accept the Terms and our Privacy Policy the first time you open it, and again whenever we publish a revision with a new acceptance key. By accepting, or by using the Service, you agree to be bound by the Terms. If you do not agree, do not use the Service.

Part One: Core Terms

1. Definitions

"Access Password" means a shared password that the Company may issue to admit writers to the Service in addition to individual sign-in, described in Section 3.2.

"Agency Tier" means the per-manuscript setting described in Section 9 that limits what the Service's AI features may do with that manuscript.

"Allowance" means a monthly fair-use budget for an AI feature under a Plan, as described in Section 8.4.

"Certificate" means the signed statement issued by the Company with a Certified Export, as described in Section 9.

"Certified Export" means the plain-text export of a manuscript accompanied by a Certificate.

"Closure Notice" means a notice shown in the Service, and on prosa.so, telling you that the Service, or a Plan, will be withdrawn on a stated date, as described in Section 16.

"Manuscript Data" means any text, manuscript, story content, notes or other written material that you type into, paste into or import into the Service, including every draft and the scene and chapter structure you give it.

"Output" means the analytical material the Service produces from your Manuscript Data: rosters of who and what is present in a scene, Story Bible entries and their references, answers to your questions, consistency findings, watch-list items and proposed chapter and scene structure on import. Output never includes prose written by the Service, because the Service does not write prose.

"Plan" means one of the Free, Hobby, Pro or Pilot plans described in Section 8.1.

"Polar" means Polar Software Inc. or its affiliate acting as merchant of record for paid Plans, as described in Section 8.2.

"Subscription" means a paid Plan bought through Polar.

2. Eligibility

2.1 Age

You must be at least 18 years old to use the Service. By using it you represent and warrant that you are. We do not verify age and do not collect your date of birth; we rely on this warranty, because the Service is a paid tool for writing long-form fiction, is behind sign-in and an Access Password, and offers nothing directed at children.

2.2 Sanctions and export controls

The Service must not be used by any person or entity that is (a) located in, ordinarily resident in or organised under the laws of a country or territory subject to comprehensive sanctions maintained by the United Kingdom or the United States; (b) named on a restricted-party list maintained by the UK Office of Financial Sanctions Implementation, the US Office of Foreign Assets Control or the US Bureau of Industry and Security; or (c) otherwise prohibited from using the Service under applicable sanctions or export-control law. By using the Service you represent and warrant that none of these applies to you. We also check, on every request, the country your connection comes from, as reported by our edge provider, and refuse requests from countries subject to comprehensive sanctions (at the date of these Terms: Cuba, Iran, North Korea and Syria) whatever the account's home country. We may suspend or close any account that we reasonably believe breaches this Section.

2.3 Geographic availability

The Service is offered to people based in the United Kingdom and the United States. The country your connection came from when you first accepted these Terms is recorded on your account as your home country and decides eligibility. It does not change when you travel, so you can use the Service from abroad, subject to Section 2.2. If your recorded home country is not one where the Service is offered, the Service will tell you it is unavailable and your account and manuscripts are left unchanged; you may ask support@prosa.so to review it, and we may admit an account by exception, or correct a home country that was recorded wrongly, at our discretion. Accounts opened before 5 September 2026 keep their access. Wherever you use the Service, you are responsible for compliance with your local law.

3. Accounts and access

3.1 Your account

You sign in with an email address or a Google account through our authentication provider, Clerk. You must give accurate information and keep it current. You are responsible for your credentials and for everything done under your account, and you must tell us at support@prosa.so promptly if you believe it has been used without your permission.

3.2 The Access Password

The Company may place the Service behind a shared Access Password in addition to your individual sign-in, for example while access is limited or during a rollout. The Access Password is confidential. You must not share it with anyone or publish it. We may change it at any time; when we do, every browser that remembered the old password is signed out and you will be asked for the new one.

3.3 Accepting the Terms

The first time you open the Service it asks you to accept the Terms and the Privacy Policy. We record your user id, the acceptance key shown at the top of this page and the time. When we publish a revision with a new acceptance key the Service will ask you to accept again before you can continue; that is how we give notice of changes to these documents (see Section 14).

3.4 One owner per manuscript

Each manuscript belongs to one account. The Service has no sharing or invitation feature in this version, and nothing in the Terms grants anyone else access to your work.

3.5 How the contract is formed

The Terms become binding between you and the Company when you accept them in the Service. We record that acceptance but do not file the contract in a form you can retrieve; this page always shows the current version and its history, and you can save or print it. If you buy a paid Plan, Polar's checkout shows you a summary of the order and lets you correct it before you confirm, and Polar sends you a confirmation of the order. The Terms are offered in English only.

4. Description of the Service

4.1 What the Service does

Prosa is a browser application for novelists. In this version it provides:

• The editor. A manuscript editor with version history. Your text is held live on a collaborative document server operated by Tiptap and mirrored into the Company's own database.
• Import. Upload a Word (.docx) file of up to 50 MB. The file is converted to text and the file itself is discarded. An AI model proposes chapter and scene boundaries, which you confirm or change before the manuscript is created.
• Export. A Word document of any draft, built in your browser from your own scenes. Nothing is sent to a server to produce it.
• Certified export. A plain-text export accompanied by a Certificate, described in Section 9.
• Story Bible. Characters, places and other entities extracted from your manuscript, each with references back to the passages that support them.
• Margin scene readings. On request, a model reads one scene of up to 10,000 words and returns a roster of who and what is present in it.
• Shepherd. Ask questions about the whole book, run whole-book consistency checks, and keep a watch list of things to check on future drafts. Questions, answers and findings are kept with the manuscript, and findings are shown for you to accept or dismiss.
• Agency Tiers. A per-manuscript control over what the AI features may do, described in Section 9.
• Feedback. A link from Settings that opens an email to the Company, described in Section 6.4.

The Service runs in the current versions of mainstream desktop browsers over an ordinary internet connection. Nothing is installed on your device, and the Service applies no technical protection measures to your exported files.

4.2 The Service reads; it does not write

Every AI feature in this version is analytical. The Service does not draft, rewrite, autocomplete, suggest or generate prose, and it never changes the words of your manuscript. It is an editorial aid. It is not a definitive verifier of facts, a substitute for human proofreading or a replacement for professional editorial advice.

4.3 Continuous development

The Service is developed continuously. Features, limits and Allowances may be added, changed or withdrawn as described in Section 14, and a change that reduces an Allowance or a limit of a paid Plan always carries the 30 days' notice and the right to cancel with a pro-rata refund in Section 14.1, and the Service may at any time contain defects that we are working to fix. We use reasonable efforts to fix reported problems but do not guarantee that every problem will be fixed or that the Service will be uninterrupted.

4.4 Third-party providers

The Service depends on third-party providers: hosting, the collaborative document server, authentication, billing, and AI inference. The providers are named, with what each receives, in the Privacy Policy. You acknowledge that (a) the availability and performance of the Service depend in part on those providers, which we do not control; (b) we are not liable for interruption or degradation caused by a provider's outage except to the extent it results from our failure to take reasonable contingency measures; and (c) we may change providers, provided any replacement AI provider is bound by data-processing terms no less protective than those in Section 6.

5. AI disclosure and limitations

5.1 Nature of Output

The Service produces Output using probabilistic AI models hosted by third parties. You acknowledge that: (a) Output may be inaccurate, incomplete, inconsistent or unreliable, which is an inherent characteristic of such models; (b) you are solely responsible for reviewing and verifying Output before relying on it; (c) we make no warranty as to the accuracy, completeness or reliability of any Output; and (d) Output is an aid to your judgement, not a replacement for it.

5.2 No endorsement

Output is produced by automated pipelines. It does not represent the views or editorial judgement of the Company, its directors or staff, or of any AI provider. We do not review Output before it is shown to you, and no statement in an Output is an assertion of fact or opinion by the Company.

5.3 No automated decisions

The Service does not make decisions about you that have legal or similarly significant effects. Every finding is presented for you to accept or dismiss.

6. Data processing and the no-training covenant

6.1 No training on your work

We do not use your Manuscript Data or Output to train, fine-tune or otherwise improve any AI model, whether ours or anyone else's. Your work is processed only to produce the specific Output you request. Where we send Manuscript Data to third-party AI providers we use only providers whose terms exclude the use of API inputs for model training, and we enable zero-retention options where a provider offers them. The providers, and the model hosts they route to, are listed in the Privacy Policy.

6.2 What "service improvement" means

Our right to provide and maintain the Service does not include training any model on your work. Service improvement is limited to operational maintenance, performance monitoring, bug fixing and security work using non-content signals: request ids, routes, status codes, timings and the identity of the model used. Our logging is designed to exclude prose, email addresses and manuscript identifiers by construction. Sending your Manuscript Data to an AI provider to produce the Output you asked for is part of providing the Service, not service improvement.

Separately, we may review questions put to Shepherd and the answers it gave, including the manuscript excerpts it cited as evidence, in order to improve how the Service answers. That review is done by people, changes our prompts, retrieval and evaluation material by hand, and never feeds your text into the training or fine-tuning of any model. The Privacy Policy explains the basis for this review and how to object to it.

6.3 Aggregate data

We may produce aggregate or anonymised statistics about use of the Service, provided they contain no Manuscript Data and nothing from which your manuscript could be reconstructed. Such statistics belong to the Company.

6.4 Feedback

Feedback goes by email to support@prosa.so. The Support page in Settings opens your own mail client with only the subject filled in. The Service stores nothing about the message. You keep ownership of what you write; by sending it you allow the Company to use it to understand and improve the Service, and we will not publish it or attribute it to you without asking.

7. Intellectual property

7.1 Your Manuscript Data

You retain all right, title and interest in your Manuscript Data. Nothing in the Terms transfers ownership of your work to the Company.

7.2 Company property

The Company owns the Service, including its code, interfaces, algorithms, the format of its Output, the Certificate format and its verification keys, and all improvements to any of them, including improvements derived from non-content signals and from the review described in Section 6.2.

7.3 Licence from you to us

You grant the Company a non-exclusive, non-transferable, limited licence to store, process, analyse and transmit your Manuscript Data solely to provide the Service to you, including by sending it to the collaborative document server and, when you use an AI feature, to the AI providers named in the Privacy Policy, subject always to Section 6. The licence lasts while your work is in the Service and for such further period as is reasonably needed to complete a pending operation, fulfil a deletion request or meet a legal obligation.

7.4 Output

Ownership of Output is addressed in the applicable addendum. In every case you keep ownership of your Manuscript Data, and Output that reproduces passages of your manuscript (for example a Story Bible reference or an excerpt cited by Shepherd) reproduces your work, not ours.

7.5 The Certificate

A Certificate is the Company's signed statement about the Service's own records. It is not your work and not an Output. You receive the licence described in Section 9.5 to use it.

8. Plans, allowances and payment

8.1 Plans

The Service is offered on four Plans. The limits below are those enforced by the Service in this version.

The Pilot plan is a complimentary plan, shown under that name in the Service, that the Company grants and withdraws at its discretion, for example to early writers and reviewers. It is never sold. It ends automatically if you buy a paid Plan; the Service warns you of this before it sends you to checkout.

8.2 Polar as merchant of record

Paid Plans are sold by Polar as merchant of record. When you buy a Subscription you contract with Polar for the purchase: Polar displays the price and renewal terms, takes your payment details, collects any applicable tax, issues invoices and receipts, sends billing emails and handles refunds under its own customer terms, which it shows you at checkout. The Company does not see or store your card details. When Polar tells us that a Subscription is active we grant the corresponding Plan to your account.

8.3 Prices

Prices for the Hobby and Pro plans, in monthly and annual variants, are shown on Polar's checkout page before you confirm a purchase, and on prosa.so. Any figure shown on prosa.so is indicative; the checkout page governs. Prices shown to consumers in the United Kingdom include VAT.

8.4 Allowances

Plans that include AI features carry two monthly Allowances measured by what each request costs the Company to run, not by the number of requests: one shared by whole-book consistency checks and Shepherd questions, and one for Margin scene readings, with each reading capped at 10,000 words of scene text. The Service shows how much of each Allowance remains. Allowances reset each month and unused Allowance does not carry over. They are fair-use budgets; a reduction is a change to what a paid Plan includes and carries the notice and exit rights in Section 14.1. When an Allowance is used up the affected features pause until it resets; the editor, import and export are never metered.

8.5 Billing and renewal

A Subscription is billed in advance and renews automatically at the end of each billing period, monthly or annual as chosen, until cancelled. Renewal terms are disclosed by Polar before you complete your first purchase and confirmed by Polar afterwards. Reminders about renewal, where required by law, are sent by Polar to the email address you gave at checkout.

8.6 Cancelling and changing Plans

You cancel or change a Subscription in Polar's billing portal, which opens from Settings in the Service, or by emailing support@prosa.so, which we will act on with Polar. Cancellation takes effect at the end of the current billing period and your Plan then returns to Free. Unless applicable law or the applicable addendum says otherwise, no refund is made for the unused part of a billing period.

8.7 Failed payments

If Polar cannot collect a renewal it marks the Subscription past due and retries under its own schedule. Your Plan continues in full while the Subscription is past due. Only when Polar marks it cancelled or unpaid does your Plan return to Free. Nothing is deleted when a Plan changes; if you then hold more manuscripts than the Free plan allows, you can still open and export them but cannot create more until you are within the limit.

8.8 Changes to fees

We may change the price of a Plan on at least 30 days' notice given in the Service and on prosa.so. A change takes effect from your next billing period after the notice period. If you do not accept the new price you may cancel before it takes effect.

8.9 Withdrawal mid-cycle

If a Closure Notice withdraws the Service, or a Plan, part-way through a billing period for which you have paid, we will arrange with Polar a pro-rata refund of the unused days of that period, calculated daily and paid to your original payment method within 14 days of the closure date. This is in addition to any right you have under law or the applicable addendum.

8.10 Your statutory rights

The arrangement with Polar does not reduce any right you have by law against the Company as the provider of the Service. If the Service does not conform to the Terms, or to the description we give of it, the remedies described in the applicable addendum are available to you from us, and any refund due will be arranged through Polar. For a refund about the quality or availability of the Service, contact support@prosa.so and we will arrange it; for a billing error or a duplicate charge, contact Polar through the billing portal, or us, and we will pass it on.

9. Agency Tiers and the certified export

9.1 Agency Tiers

Each manuscript has an Agency Tier that you choose and can change at any time from the manuscript's settings. In this version three tiers are offered: T0 "No assistance" (no AI feature may read the manuscript), T1 "Mechanical assistance", and T2 "Analytical assistance" (the Story Bible, Margin, Shepherd and consistency features may read it). Higher tiers exist in the Service's design but cannot be switched on in this version. The Service records every tier change, with its time, on the manuscript's lineage.

9.2 What a Certificate says

When you request a Certified Export, the Service takes an immutable snapshot of the manuscript's text and issues a Certificate stating the highest Agency Tier that was ever switched on for that manuscript in Prosa before the export. The Certificate is signed with the Company's key. It is issued once per export; requesting the Certificate again returns the same Certificate.

9.3 What a Certificate cannot say

A Certificate attests only to the Service's own records. It cannot attest to anything that happened outside Prosa: other tools, browser extensions, local models, collaborators, text pasted in from elsewhere, or anything that happened to the text before it was imported. Where a manuscript was created by importing text that was not itself Prosa-certified, the Certificate records that origin as "unverified". A Certificate is not proof of the absence of AI.

9.4 How you may describe a Certificate

You may show a Certificate to publishers, agents, competitions, readers or anyone else together with the export it covers. You must not describe a Certificate, or a manuscript because of it, as proof that no AI was used, as "AI-free" or "human-written", or as a grade of quality. The Service itself will not display such wording. You may state accurately what the Certificate says: that within Prosa, nothing above the certified tier was switched on for that manuscript before the export.

9.5 Licence to the Certificate

The Certificate format and the verification keys, which we publish so that anyone can verify a Certificate offline, belong to the Company. We grant you a non-exclusive, perpetual, royalty-free licence to use, copy and distribute each Certificate issued to you together with the export it covers.

9.6 Snapshots and deletion

Certified Export snapshots are immutable. If the manuscript is later deleted under Section 15, the snapshot text is purged through an audited erasure and the Company keeps only an erasure record containing the Certificate's identifiers, so that a Certificate presented afterwards can still be recognised as one we issued.

10. Acceptable use

10.1 Prohibited conduct

You must not: (a) use the Service for any unlawful purpose or in breach of any law; (b) upload content that is defamatory, obscene, infringing or otherwise unlawful; (c) reverse-engineer, decompile or disassemble the Service, except to the extent the law allows you to regardless of this clause (for example decompilation for interoperability under section 50B of the Copyright, Designs and Patents Act 1988); (d) interfere with or disrupt the integrity or performance of the Service; (e) use the Service to build a competing product; (f) share your credentials or the Access Password with anyone, or let anyone else use your account; (g) upload, transmit or store any content that depicts, promotes or facilitates the sexual exploitation or abuse of minors or constitutes child sexual abuse material, which we will remove immediately, close the account, and report to the relevant authorities; (h) upload, transmit or store content that constitutes hate speech, including content that promotes or incites violence, hatred or discrimination against any person or group on the basis of a protected characteristic; or (i) use the Service in any way that facilitates or promotes the conduct in this Section.

10.2 Suspension for breach

Without limiting Section 15.4, we may suspend or restrict your access immediately and without notice if we reasonably believe you have breached Section 10.1, and may close the account for serious or repeated breaches. Suspension does not relieve you of any fees due to Polar.

11. Your warranties and indemnity

11.1 Warranties

You represent and warrant that: (a) you have all rights, licences and permissions needed to place your Manuscript Data in the Service and to have it processed as described; (b) your Manuscript Data does not infringe the intellectual property, privacy or other rights of any third party; (c) your Manuscript Data is not defamatory, obscene or otherwise unlawful; and (d) you will comply with all applicable law in using the Service.

11.2 Indemnity

You agree to compensate the Company and its officers, directors, employees and agents for losses, liabilities, costs and expenses, including reasonable legal fees, that they suffer under a final judgment, or a settlement you have agreed to, in a third-party claim arising out of (a) your breach of the Terms; (b) your Manuscript Data, where it is found to infringe or misappropriate a third party's rights; or (c) your use of the Service in breach of applicable law. This applies only to the extent the loss was caused by you, and not to the extent it was caused by the Company's own breach, negligence or unlawful act, or by the way the Service processed your Manuscript Data. If you are a consumer, nothing in this Section makes you liable for more than the loss a court would award against you for the same conduct.

12. Limitation of liability

The specific limits and exclusions are set out in the applicable addendum. In every case, to the maximum extent permitted by law: (a) the Company is not liable for indirect, incidental, special, consequential or punitive damages, including loss of profits, data or business opportunity, arising out of or in connection with the Service; and (b) the Company is not liable for any loss or claim arising from reliance on Output without independent verification.

13. Privacy

Our Privacy Policy explains what personal data the Service holds, where your manuscript text goes, who processes it and how long each thing is kept. By using the Service you acknowledge that you have read it. Where Manuscript Data contains personal data we process it in accordance with applicable data-protection law and the Privacy Policy. Our Cookie Policy describes what the Service stores in your browser.

14. Changes to the Service and to the Terms

14.1 Changes to the Service

We may add, change or withdraw features, limits and Allowances in order to improve the Service, to reflect changes in what our providers offer or charge, to respond to security or legal requirements, or to keep the Service sustainable. Where a change materially reduces what a paid Plan includes we will give at least 30 days' notice in the Service and on prosa.so, and you may cancel before it takes effect; if you do, we will arrange with Polar a pro-rata refund of any period you have paid for beyond the date the change takes effect.

14.2 Changes to the Terms

We may revise the Terms to reflect changes in the Service, in the law, in our providers, or in how we operate, or to correct errors. A revision that materially affects your rights or obligations is published on this page with a new version number and acceptance key, and notice is shown in the Service at least 30 days before it takes effect, except where a shorter period is needed to comply with law or to address a security risk. When the acceptance key changes the Service will ask you to accept the revised Terms before you continue. If you do not accept, you may stop using the Service and export your work under Section 16.3; a paid Subscription can be cancelled with Polar.

14.3 How we give notice

We do not operate an email service. Notices from the Company are given in the Service and on prosa.so. Emails about sign-in come from Clerk and emails about billing come from Polar; each of those companies sends them under its own terms. Notices to the Company go to support@prosa.so.

15. Archiving, deletion and termination

15.1 Archive and restore

You can archive a manuscript and restore it within your Plan's limits. Archiving does not delete anything.

15.2 Deletion of a manuscript or account

The Service does not yet delete anything by itself. To delete your account and every manuscript in it, use the "Request account deletion" control in Settings, which records the request and notifies a person at the Company, or email privacy@prosa.so from the address on your account. To delete a single manuscript, email. We will complete a verified deletion request within 30 days across the Company's own systems, the collaborative document server, the authentication provider and, where you have a Subscription, Polar, subject to Section 9.6 and to any legal obligation to retain particular records. Before we delete, we will remind you to export.

15.3 Termination by you

You may end the Terms at any time by cancelling any Subscription with Polar, requesting deletion under Section 15.2 and ceasing to use the Service.

15.4 Termination by us

We may suspend or close your account immediately, without notice, if (a) you breach the Terms; (b) we are required to by law; or (c) we reasonably believe your use poses a security risk. We may also close accounts under a Closure Notice, subject to Section 16.

15.5 Effect of termination

On termination your right to use the Service ends. Where termination follows a Closure Notice, Section 16 applies. Otherwise we will delete your Manuscript Data within 30 days of termination, subject to Section 9.6 and any legal obligation to retain particular records. Sections 5, 6.1, 7, 9.4 to 9.6, 11, 12, 16.3 and the applicable addendum survive termination.

16. Withdrawal of the Service

16.1 Notice

If we decide to withdraw the Service, or a Plan, we will publish a Closure Notice in the Service and on prosa.so at least 30 days before the closure date, together with instructions for exporting your work and, where a replacement Plan exists, for moving to it.

16.2 Export window

From the Closure Notice until at least 30 days after the closure date you will be able to sign in, open your manuscripts and export them. During that window after the closure date the Service is read-only and the AI features are not available. Section 8.9 applies to any paid period the closure interrupts.

16.3 Exporting your work

At any time, and throughout the export window, you can export every draft of every manuscript as a Word document and any manuscript as a Certified Export, using the Service's export features, without charge. Export is complete for your manuscript text. A copy of your account record, usage ledger and Output, including Shepherd questions and answers, is not produced by the Service; we will supply it on request to privacy@prosa.so in a machine-readable format within one month, as described in the Privacy Policy.

16.4 After the window

At the end of the export window we will delete your Manuscript Data under Section 15.2, subject to any legal obligation to retain particular records.

17. General

17.1 Entire agreement

The Terms, the applicable addendum, the Privacy Policy and the Cookie Policy are the entire agreement between you and the Company about the Service and replace any earlier agreement, including the pilot-release terms that preceded these. Your purchase of a Subscription is a separate contract with Polar under Polar's terms. Nothing in this Section excludes liability for fraud, or limits anything we have said or written about the Service that the law treats as a term of our contract with you.

17.2 Severability

If any provision of the Terms is held invalid or unenforceable, it will be enforced to the maximum extent permitted and the rest remains in force.

17.3 No waiver

Our failure to enforce any provision is not a waiver of it.

17.4 Assignment

You may not assign or transfer your rights or obligations under the Terms without our written consent. We may assign ours to a successor to our business, provided your rights under the Terms are not reduced by the transfer, and will give notice under Section 14.3 if we do.

17.5 Force majeure

We are not liable for delay or failure caused by events beyond our reasonable control, including natural disasters, pandemics, war, terrorism, government action, or failures of the internet or of the third-party infrastructure on which the Service runs.

Part Two: Jurisdiction-Specific Addenda

Addendum A: United Kingdom

This Addendum applies if you are resident in the United Kingdom. It supplements and, where stated, modifies the Core Terms.

A1. Governing law and jurisdiction

The Terms and any dispute or claim arising out of or in connection with them, including non-contractual disputes, are governed by the law of England and Wales. The courts of England and Wales have exclusive jurisdiction, subject to any mandatory consumer-protection rule that lets you bring proceedings where you live. If you are resident in Scotland or Northern Ireland, you may bring proceedings in the courts there, and nothing in this choice of law takes away a right that the consumer law of Scotland or Northern Ireland gives you.

A2. Consumer rights

Nothing in the Terms affects your statutory rights under the Consumer Rights Act 2015 or other applicable UK consumer law. Where the Terms conflict with a mandatory statutory right, the right prevails.

A2.1 Right to cancel

Under the Consumer Contracts (Information, Cancellation and Additional Charges) Regulations 2013 you may cancel a Subscription within 14 days of buying it without giving a reason. Tell us by a clear statement, for example by email to support@prosa.so, or tell Polar through its billing portal; you may use the model form in Schedule 1 but need not. Because Polar is the seller of record, any refund due is issued by Polar. This right is in addition to the pro-rata refund in Section 8.9 of the Core Terms.

A2.2 Immediate access

Your Plan is switched on as soon as Polar confirms payment, so that you can use it during the cancellation period. Before that happens you will be asked to confirm that you want the Service to start at once and that you understand you will lose the right to cancel once it has been fully provided. If you cancel during the period after asking for immediate access, you pay a proportionate amount for the part of the period already provided and the rest is refunded.

A2.3 Cancellation form

Schedule 1 contains a model cancellation form. Using it is optional; any clear statement of your decision is enough.

A2.4 If the Service is faulty

Under the Consumer Rights Act 2015 the Service must be of satisfactory quality, fit for purpose and as described. If it is not, you are entitled to have it repaired or replaced, and if that is impossible or not done within a reasonable time and without significant inconvenience, to a reduction in price, which may be up to the full amount you paid for the affected period. If a fault in the Service damages your device or other digital content and we failed to use reasonable care and skill, you are entitled to a repair or to compensation. These rights are not limited by Sections 12 or A4, and refunds due under them are arranged through Polar.

A2.5 Renewal cooling-off

Where the law gives you a cooling-off period on a renewal, for example when a subscription renews after a free or discounted period or after a term of twelve months or more, you may cancel within that period and Polar will refund the renewal payment.

A3. Output ownership and licence

The Company owns the format, structure, code and methodology used to produce Output and the Certificate. The Company grants you a non-exclusive, perpetual, royalty-free licence to use, copy and distribute the specific Output produced for you. The licence is personal to you and does not extend to the Company's technology or methods. Output is a separate analytical work about your manuscript; it is not a treatment, adaptation or modification of your Manuscript Data for the purposes of UK copyright law, save that any passage of your manuscript quoted in an Output remains yours.

A4. Limitation of liability

A4.1 Exclusions

Nothing in the Terms excludes or limits the Company's liability for death or personal injury caused by negligence, for fraud or fraudulent misrepresentation, or for any liability that cannot be excluded or limited by law.

A4.2 Cap

Subject to A4.1, the Company's total aggregate liability to you under or in connection with the Terms, whether in contract, tort including negligence, breach of statutory duty or otherwise, shall not exceed the greater of (a) the total Subscription fees you paid through Polar in the 12 months before the event giving rise to the claim, and (b) £100. This cap does not apply to the remedies in A2.4 or to any other right you have as a consumer that cannot be limited by contract.

A4.3 Output

Without limiting Section 5 of the Core Terms, the Company is not liable for loss or damage arising from your reliance on Output, including Output that contains errors or omissions. You accept sole responsibility for verifying Output before relying on it.

A5. Company indemnity

The Company will indemnify you against any third-party claim that the Service itself, excluding your Manuscript Data and Output derived from it, infringes a third party's intellectual property rights, provided you notify us promptly, give us sole control of the defence and settlement, and cooperate reasonably at our expense. Our liability under this indemnity is capped under A4.2 and does not apply where we had no knowledge, or reasonable means of knowledge, of the alleged infringement.

A6. Data protection

The Company is the controller of the personal data it processes to provide the Service, under the UK GDPR and the Data Protection Act 2018. The Company stores your data in Germany with its hosting provider. In providing the Service, Manuscript Data is sent to the collaborative document server in the European Union and, when you use an AI feature, to AI providers in the United States; identity data is processed by the authentication provider in the United States. Transfers from the United Kingdom to the European Union rely on the UK adequacy regulations. Transfers to the United States rely on the UK-US Data Bridge where the provider is certified under the UK Extension to the EU-US Data Privacy Framework and otherwise on the International Data Transfer Agreement or the UK Addendum to the EU Standard Contractual Clauses. Full details are in the Privacy Policy.

A7. Illegal content

The Service has no feature by which one writer's content is shown to another. Whether or not any duty under the Online Safety Act 2023 applies to it, the Company will remove or disable access to content that constitutes a serious criminal offence under UK law, including child sexual exploitation and abuse material, terrorism content and content that incites hatred or violence, and will report child sexual abuse material to the National Crime Agency or such other authority as the law requires. Report such content to support@prosa.so.

A8. Subscription information and renewal

A8.1 Pre-contract information

Before you confirm a purchase, Polar's checkout displays the price, billing frequency, renewal terms and how to cancel. The Company's Plan limits are shown in Section 8.1 of the Core Terms and in the Service.

A8.2 Renewal reminders

Reminders that the law requires before a renewal payment, including those under the subscription-contract provisions of the Digital Markets, Competition and Consumers Act 2024 once they apply, are sent by Polar as seller of record to the email address you gave at checkout. Each states the renewal date, the amount and how to cancel. If Polar does not send a reminder that the law requires, the Company will send one through the Service, and you will not be bound by a renewal about which you were not reminded.

A8.3 Easy exit

Because the Subscription is entered into online, you can cancel it online at any time through Polar's billing portal, opened from Settings in the Service.

Addendum B: United States

This Addendum applies if you are resident in the United States. It supplements and, where stated, modifies the Core Terms. References to state privacy or consumer laws apply to the extent those laws apply to the Company. Nothing in this Addendum applies to a resident of the United Kingdom. Whether you are a United Kingdom or a United States resident is decided by the home country recorded on your account under Section 2.3, not by where you happen to be when you use the Service, so a United Kingdom writer travelling or using a US connection stays under Addendum A.

B1. Governing law

The Terms and any dispute arising out of or relating to them are governed by the laws of the State of Delaware, without regard to its conflict-of-law rules, except to the extent pre-empted by federal law. This choice does not take away any protection that the consumer law of the state where you live gives you and that cannot be waived by contract.

B2. Arbitration and class-action waiver

B2.1 Agreement to arbitrate

You and the Company agree that any dispute, claim or controversy arising out of or relating to the Terms or the Service (a "Dispute") will be resolved exclusively by binding individual arbitration administered by the American Arbitration Association under its Consumer Arbitration Rules. This agreement is to be interpreted broadly and covers claims in contract, tort, statute, fraud, misrepresentation or any other theory.

B2.2 Class-action waiver

YOU AND THE COMPANY EACH WAIVE THE RIGHT TO PARTICIPATE IN A CLASS ACTION, COLLECTIVE ACTION, PRIVATE ATTORNEY GENERAL ACTION OR ANY OTHER REPRESENTATIVE PROCEEDING. ALL DISPUTES WILL BE RESOLVED ON AN INDIVIDUAL BASIS ONLY.

B2.3 Small claims

Either party may bring an individual action in small-claims court for a Dispute within that court's jurisdiction.

B2.4 Opt-out

You may opt out of this arbitration agreement by emailing support@prosa.so within 30 days of first accepting the Terms, stating your name and the email address on your account. If you opt out, the dispute-resolution rules of applicable law apply and the rest of the Terms are unaffected.

B2.4A Exceptions

Nothing in this Section B2 prevents you from bringing a complaint to a federal, state or local agency, and nothing in it waives a right that cannot be waived by contract. If the class-action waiver in B2.2 is found unenforceable as to a particular claim, that claim will be decided by a court and not in arbitration.

B2.5 Fees

For a Dispute in which your total claim is US $10,000 or less, the Company pays all AAA filing, administration and arbitrator fees, and if the arbitrator finds your claim was brought in good faith the Company will not seek its fees or costs from you. For larger claims, fees and costs are allocated under the AAA Consumer Arbitration Rules. Nothing here limits the arbitrator's authority to award fees or costs as the law permits.

B3. Output ownership and copyright

B3.1 Assignment

The Company claims no ownership of Output. We assign to you all right, title and interest, if any, that the Company may hold in Output produced for you. The Certificate is excluded from this assignment and is licensed to you under Section 9.5 of the Core Terms.

B3.2 Copyright notice

AI-produced Output may not be protectable under United States copyright law. It is provided as is, without warranty of exclusivity or of eligibility for copyright registration.

B3.3 Three categories

The Terms distinguish (a) the Tool: the Service's code, algorithms, interfaces, Output formats and methods, owned by the Company; (b) your arrangement: any selection, coordination or creative arrangement of Output that you author, which may be yours to the extent it reflects your original expression; and (c) raw Output produced without further creative input from you, which may not be protectable and is provided without warranty as to its legal status.

B4. Cross-border data

You acknowledge and consent to the storage of your Manuscript Data in Germany and its processing in the European Union and the United States as described in the Privacy Policy, including transmission to AI providers in the United States when you use an AI feature. The Company implements appropriate safeguards for all cross-border transfers in accordance with applicable law.

B5. Disclaimer of warranties

THE SERVICE IS PROVIDED "AS IS" AND "WITH ALL FAULTS". TO THE FULLEST EXTENT PERMITTED BY LAW THE COMPANY DISCLAIMS ALL WARRANTIES, EXPRESS, IMPLIED, STATUTORY OR OTHERWISE, INCLUDING THE IMPLIED WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, TITLE AND NON-INFRINGEMENT.

THE COMPANY DOES NOT WARRANT THAT THE SERVICE WILL BE UNINTERRUPTED, ERROR-FREE OR SECURE, OR THAT DEFECTS WILL BE CORRECTED. THE SERVICE USES PROBABILISTIC ARTIFICIAL INTELLIGENCE THAT MAY PRODUCE INACCURATE OR INCONSISTENT OUTPUT. THE COMPANY MAKES NO WARRANTY AS TO THE ACCURACY, COMPLETENESS OR RELIABILITY OF ANY OUTPUT.

THE SERVICE IS AN EDITORIAL AID AND NOT A SUBSTITUTE FOR PROFESSIONAL EDITORIAL ADVICE. YOU ARE SOLELY RESPONSIBLE FOR VERIFYING OUTPUT BEFORE RELYING ON IT.

THE SERVICE RELIES ON THIRD-PARTY AI MODELS AND INFRASTRUCTURE. THE COMPANY DOES NOT CONTROL THE INTERNAL BEHAVIOUR OF THOSE MODELS AND MAKES NO WARRANTY AS TO THE PERFORMANCE, AVAILABILITY OR ACCURACY OF ANY THIRD-PARTY SERVICE.

B6. Limitation of liability

B6.1 Cap

TO THE MAXIMUM EXTENT PERMITTED BY LAW, THE COMPANY'S TOTAL AGGREGATE LIABILITY FOR ALL CLAIMS ARISING OUT OF OR RELATING TO THE TERMS OR THE SERVICE SHALL NOT EXCEED THE GREATER OF (A) THE TOTAL SUBSCRIPTION FEES YOU PAID THROUGH POLAR IN THE 12 MONTHS BEFORE THE EVENT GIVING RISE TO THE CLAIM, AND (B) ONE HUNDRED US DOLLARS (US $100).

B6.2 Consequential damages

TO THE MAXIMUM EXTENT PERMITTED BY LAW, IN NO EVENT SHALL THE COMPANY BE LIABLE FOR INDIRECT, INCIDENTAL, SPECIAL, CONSEQUENTIAL OR PUNITIVE DAMAGES, INCLUDING LOSS OF PROFITS, GOODWILL, DATA OR OTHER INTANGIBLE LOSSES, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.

B7. Mutual data-breach indemnity

If a data breach is caused by either party's failure to maintain reasonable security measures: (a) the breaching party will indemnify the other against reasonable, documented third-party costs, liabilities and expenses, including reasonable legal fees and regulatory fines, directly arising from the breach; (b) the indemnifying party's total liability under this Section is capped at the Subscription fees paid or payable by you through Polar in the 12 months before the breach; and (c) the non-breaching party must give prompt written notice and cooperate reasonably in investigation and remediation.

B8. California residents

If you are a California resident you may have additional rights under the California Consumer Privacy Act; see the Privacy Policy. Under California Civil Code Section 1789.3 you may contact the Complaint Assistance Unit of the Division of Consumer Services of the California Department of Consumer Affairs at 1625 North Market Blvd., Suite N 112, Sacramento, CA 95834, or by telephone at (800) 952-5210.

B9. Illegal content and NCMEC reporting

In accordance with 18 U.S.C. § 2258A, if the Company obtains actual knowledge of apparent child sexual abuse material on the Service it will report to the National Center for Missing & Exploited Children CyberTipline and preserve related evidence for the period the law requires. Report such content to support@prosa.so. The Company will also comply with applicable federal and state law on hate speech, threats and incitement.

B10. Authorised access

Access to the Service is permitted only through the interfaces the Company provides. You must not (a) access the Service by automated means, including bots, scrapers or crawlers, without our written consent; (b) circumvent or interfere with any security, authentication or access-control feature, including the Access Password; (c) collect data from the Service by any unauthorised automated process; (d) probe, scan or test the vulnerability of the Service; or (e) use the Service beyond the scope of authorisation in the Terms. Unauthorised access may violate the Computer Fraud and Abuse Act (18 U.S.C. § 1030) and state law, and the Company reserves all rights and remedies, including injunctive relief.

B11. Deceptive use of the Certificate

You must not use the Service, or a Certificate, to deceive. In particular you must not represent a Certificate as proof that a manuscript is "AI-free" or "human-written", present Output as human-authored analysis where that would be material to the audience, or use any Output or Certificate in a manner that would constitute an unfair or deceptive act or practice under Section 5 of the Federal Trade Commission Act (15 U.S.C. § 45).

B12. Automatic renewal disclosures

B12.1 Renewal terms

A Subscription renews automatically at the end of each billing period, monthly or annual as chosen, at the then-current price, unless cancelled before the renewal date. The price, billing frequency and renewal date are disclosed clearly and conspicuously by Polar before you complete your first purchase and are shown in Polar's billing portal thereafter.

B12.2 Consent

Before your first payment, Polar's checkout asks for your affirmative consent to the automatic renewal terms separately from your acceptance of the Terms. Polar records that consent as seller of record.

B12.3 Confirmation and reminders

After your first purchase Polar sends a confirmation to the email address you gave at checkout stating the price, the billing frequency, the automatic renewal terms and how to cancel. Where state law requires a renewal reminder, including for annual Subscriptions and for any promotional period that converts to a paid Subscription, Polar sends it. If Polar does not send a reminder that the law requires, the Company will send one through the Service, and you will not be bound by a renewal about which you were not reminded.

B12.4 Cancellation

You may cancel at any time online through Polar's billing portal, opened from Settings in the Service, or by emailing support@prosa.so. Cancellation takes effect at the end of the current billing period.

B12.5 Withdrawal

The Company may withdraw the Service or a Plan on at least 30 days' notice given in the Service and on prosa.so. If withdrawal interrupts a paid billing period, Section 8.9 of the Core Terms applies. These statements form part of the material terms of the automatic renewal for the purposes of applicable state automatic-renewal law, including the California Automatic Renewal Law (Business and Professions Code Section 17600 et seq.).

Contact

Thornwick Studios Limited, Unit 13 Freeland Park, Wareham Road, Lytchett Matravers, Poole, BH16 6FA, England. Questions about the Terms, the Service and billing: support@prosa.so. Questions about personal data: privacy@prosa.so.

Schedule 1: Model cancellation form

Complete and return this form only if you wish to cancel a Subscription under Addendum A, Section A2.1.

To: Thornwick Studios Limited, Unit 13 Freeland Park, Wareham Road, Lytchett Matravers, Poole, BH16 6FA, England; support@prosa.so

I hereby give notice that I cancel my contract for the supply of the following service: Prosa subscription (Hobby or Pro; monthly or annual).

Ordered on: ______________________

Name of consumer: ______________________

Email address on the account: ______________________

Signature of consumer (only if this form is sent on paper): ______________________

Date: ______________________

Version history

• 1.0.1, 1 October 2026. The Support page described as built: it opens your own mail client with only the subject filled in and adds no diagnostics. Acceptance key unchanged.
• 1.0.0, 5 September 2026. First public-release terms, including the home-country and sanctions checks the Service now applies (Sections 2.2 and 2.3), rewritten to describe the Service as built: Polar as merchant of record; Free, Hobby, Pro and the complimentary Pilot plan; monthly Allowances; Agency Tiers and the certified export; the Access Password; feedback by email; human review of Shepherd questions and answers, never for training; notice in the Service rather than by email; storage in Germany; consumer-law clauses on contract formation, statutory remedies, renewal cooling-off, indemnity limits and reasons for changes. Removed the pilot-period, transition-period and pilot-defect provisions, the issue-reporting feature, the graph visualisation, in-app cancellation and Stripe. Acceptance key terms-2026-09.
• 0.3.0, 3 June 2026. Pilot-release terms; company renamed to Thornwick Studios Limited.
• 0.2.0 and 0.1.0. Earlier pilot terms under the TrueTale name.