Thornwick Studios Limited · Prosa
Privacy Policy
What personal data Prosa holds, where your manuscript text goes, who processes it, how long each thing is kept, and how to exercise your rights. Covers the application at write.prosa.so and the website at prosa.so.
This Privacy Policy explains how Thornwick Studios Limited ("Thornwick Studios", "we", "us" or "our") collects, uses, shares and protects personal data when you use Prosa. Parts A and B cover the Prosa application at write.prosa.so and the services behind it (the "Service"). Part C covers the marketing website at prosa.so (the "Website"). Part D contains the jurisdiction-specific addenda for the United Kingdom and the United States.
We have written this to be exact about one thing above all: where the text of your manuscript goes. Section 3 is that description.
Questions go to privacy@prosa.so or to the postal address in Section 1.
Part A: The Prosa application
1. Who we are
Thornwick Studios Limited is a private limited company registered in England and Wales, company number 16682779, with its registered office at Unit 13 Freeland Park, Wareham Road, Lytchett Matravers, Poole, BH16 6FA, England. We are the controller of the personal data described in this Policy. Prosa is a Thornwick Studios product. Our data-protection contact is privacy@prosa.so.
2. What we hold, where, and for how long
The table lists every category of personal data the Service holds, who holds it, in which country, and how long it is kept. "Life of the account" means until your account is deleted under Section 8. Where we say a period is not enforced automatically, the data stays until we delete it on request or under Section 8.
| Category | What it contains | Held by | Where | Kept for |
|---|---|---|---|---|
| Identity | Name, email address, sign-in credentials or Google identity, session cookies | Clerk, our authentication provider | United States | Life of the account |
| Account record | Your Clerk user id, account status, editor theme, the "share usage" setting, the version and time of your acceptance of the Terms, and any data-request rows (kind, state, when you asked, when and by whom it was closed, and a short note of what was done) | Thornwick Studios | Germany | Life of the account |
| Home country | The country your connection came from when you first accepted the Terms (a two-letter country code, not the address itself), how and when it was set, and, if we admitted your account by exception, the reason, who granted it, when, and any expiry or revocation | Thornwick Studios | Germany | Life of the account; an exception is kept as a record even after revocation |
| Sign-up campaign | If the link you signed up from carried campaign tags, those tags: the website, ad or post that brought you (for example "meta", "paid_social", and the names of the campaign and the ad). They describe the link, not you or your device | Thornwick Studios | Germany | Life of the account |
| Billing link | Polar customer id, subscription id, product id, plan, status, period dates, whether cancellation is pending | Thornwick Studios | Germany | Life of the account |
| Payment details | Card, billing address, invoices, tax records | Polar, as merchant of record | See Section 6 | Polar's retention, including tax-record periods |
| Manuscript text | Everything you type, paste or import: every draft, and the chapter and scene structure | Tiptap Cloud (live document and version history) and Thornwick Studios (scene copies, search passages, per-scene dossiers, immutable certified-export snapshots) | Tiptap: European Union; Thornwick: Germany | Life of the account, or until a manuscript is deleted on request. Archiving keeps everything |
| AI outputs | Scene rosters, consistency findings, watch items, proposed structure on import | Thornwick Studios | Germany | Life of the account, or until the manuscript is deleted |
| Shepherd questions and answers | Every question you put to Shepherd, the answer it gave, and the manuscript excerpts it cited as evidence | Thornwick Studios | Germany | Kept with the manuscript for the life of the account, or until the manuscript is deleted |
| Usage ledger | One row per metered action: the kind of action, its cost to us, outcome and time, keyed by your user id | Thornwick Studios | Germany | Life of the account |
| Import previews | File name, size, type and hash of an uploaded Word file, and its converted text | Thornwick Studios | Germany | Converted text is cleared when the manuscript is created; previews expire automatically |
| Operational logs | Structured events: request ids, routes, status codes, durations, the alias of the model used. The log format blocks user ids, email addresses, manuscript ids and prose. One event, recorded when you send feedback, includes your user id | Datadog | European Union | 15 days |
| Operational evidence | Webhook receipts and index bookkeeping used to reconcile the Service with Tiptap and Polar | Thornwick Studios | Germany | 30 days |
| Usage counts (every account) | Which screens and features are used, timings, errors, browser and device type, against an identifier derived from your connection and browser that PostHog replaces daily and that is never linked to your account. Nothing is stored on your device | PostHog | European Union | PostHog's project retention; cannot be traced to you |
| The Prosa Letter (optional) | Only if you ask for it: whether you are subscribed, and a record of each choice you make about it (yes or no, when, where you made it and the version of the wording you were shown). While you are on the mailing list, your email address, your plan and whether you have unsubscribed are held by our mailing-list provider, which sends each letter | Thornwick Studios (your choices); Resend (the mailing list) | Thornwick: Germany; Resend: United States | Your choices for the life of the account. After you unsubscribe, your address stays on the list marked unsubscribed, which is how we make sure you are not emailed again; it is deleted with your account |
| Internal reports | A daily report of how the Service was used and where it failed, sent by email to Thornwick Studios staff only: counts of actions and failures, and for each recent sign-up the account id, time, home country, sign-up campaign and plan | Resend, which delivers it, and the mailboxes of the staff it is sent to | Resend: United States | Resend's retention for delivered messages; in our mailboxes until deleted |
| Analytics cookies and session recordings (optional) | Only if you turn on "Allow analytics cookies and session recordings": the same events linked to your account, a device identifier stored in your browser, and session recordings of the interface with all text and inputs masked | PostHog | European Union | Life of the account, or until you switch it off and ask us to delete it |
| Browser storage | Clerk session cookies; a small set of preferences; a recovery copy of each manuscript you open in the editor, including changes not yet saved to our servers (Section 3); and, only if you turn analytics on, PostHog's identifiers | Your browser | Your device | Cookies and preferences until you clear them. The recovery copy stays after you sign out and is removed when a different Prosa account signs in on that browser or when you clear the site's data. See the Cookie Policy |
Two analytics modes. For every account, the Service counts how it is used in a cookieless mode: nothing is stored on your device, the identifier changes daily and is never linked to your account, and there is no session recording. If you turn on "Allow analytics cookies and session recordings", once on first use or later under Privacy in Settings, the Service also sets an analytics cookie, links events to your account and records sessions. That switch is your consent and you can withdraw it in the same place at any time. Session recordings mask all text and every input in your browser before anything is sent, so a recording shows the shape of the screen and never the words of your manuscript, your Shepherd questions or anything you type. In both modes, only a fixed list of content-free events is sent; automatic capture of clicked text is off. The Cookie Policy describes exactly what is stored and collected. There are no advertising or marketing pixels.
The Prosa Letter. Our only marketing email is The Prosa Letter: news about Prosa, notes on writing and occasional offers, about once a month. You get it only if you ask for it, by ticking its box when you accept the Terms or by turning on "Email me The Prosa Letter" under Privacy in Settings; neither is ever ticked for you. Every letter has an unsubscribe link that works in one click without signing in, and unsubscribing there turns the switch in Settings off; turning the switch off stops the letters too. The letters carry no tracking pixel and their links are not rewritten to track clicks. We never use your manuscripts, your Shepherd questions or anything else you write in Prosa to decide who receives a letter or what it says; your plan is used only to address a letter about plans to the writers it concerns.
Your Shepherd questions persist. A question you ask Shepherd is not a passing exchange. It is stored with the manuscript alongside the answer and the excerpts the answer relied on, so that you can return to it, and it stays until the manuscript or the account is deleted. We name this separately because a writer may not expect a question to be kept.
Feedback. Feedback and support go by email to support@prosa.so. The Support page in Settings opens your own mail client with only the subject filled in. The Service itself sends and stores nothing; your email is held in our support mailbox for as long as needed to deal with it, and for no more than 24 months.
Manuscripts may contain personal data about others. A novel can describe real people, and it can reveal things that data-protection law treats as special-category data: health, beliefs, sexuality, ethnicity, politics. We do not ask for this and do not use it for anything except the features you run. Section D1.3 explains the legal basis.
3. Where your manuscript text goes
This is the complete list. Nothing else receives prose.
- The editor. As you type, your text is held on a collaborative document server run by Tiptap (Tiptap Cloud), which also keeps the version history you see in the editor. Tiptap's servers are in the European Union. Tiptap notifies our servers of changes, and we keep a copy of each scene in our own database in Germany.
- Your own browser, on each device you write on. The editor keeps a recovery copy of each manuscript you open, including changes that have not yet reached our servers, in your browser's storage (IndexedDB) on that device, so that work typed while the connection drops is not lost. It is not sent anywhere. It stays after you sign out, because it may hold the only copy of your latest changes, and it is removed when a different Prosa account signs in on that browser or when you clear the site's data for write.prosa.so. Anyone who can use that browser profile can read it, so write only on devices you trust, and clear the site's data before handing a device to someone else.
- Our own services, in Germany. From those scene copies we keep a search index of prose passages, a per-scene dossier used by Margin, the consistency runs and their findings, and, when you request a certified export, an immutable snapshot of the manuscript at that moment.
- AI providers, when you use an AI feature. When you run Import structure detection, a Margin scene reading, a Shepherd question or a consistency check, the scene text or excerpts needed for that request are sent through our own gateway to an AI provider and the result comes back. We use OpenRouter, a router that forwards each request to one of a fixed list of model hosts we have approved. Every request we send OpenRouter carries three instructions: route only to a host on our list, route only to hosts that do not train on inputs, and route only to hosts that do not retain your text after answering (a host may hold it in memory for a few minutes while it works). OpenRouter tells us which host answered, and our gateway refuses any answer from a host not on the list and records the host against the request, so we can say afterwards which company handled it. These restrictions are terms of our agreement with OpenRouter and rest on OpenRouter's agreements with, and classification of, each host; we cannot inspect a host's internal systems ourselves. The approved hosts are Amazon Web Services, Anthropic, Baseten, Cerebras, Deep Infra, Fireworks AI, Google, Groq, Inception Labs, Lambda, Microsoft, OpenAI, Parasail, SambaNova, Together AI, TypeSafe AI and xAI, all in the United States, and Mistral AI and Nebius in the European Union. (Our configuration lists Google twice, once for each of its two services, so it holds twenty entries for these nineteen companies.) Whoever developed a model, your text goes only to the approved host that runs it; a model's developer receives nothing unless it is itself one of the approved hosts. OpenRouter is a United States company. Text is sent for inference only; no feature in this version writes anything back into your manuscript.
- In transit only. Cloudflare sits in front of every hostname as a proxy. It terminates the encrypted connection at its edge and forwards each request to our servers over an encrypted connection, so your traffic, including manuscript text as you type, passes through Cloudflare's network in transit. Cloudflare does not store it.
- Nowhere else. Word export runs entirely in your browser; nothing is sent to a server to produce it. Our logs and metrics are built on a format that refuses prose, so Datadog never receives manuscript text.
No training. We do not use your manuscript or the outputs derived from it to train, fine-tune or improve any AI model, ours or anyone else's. We use only AI providers whose terms exclude training on API inputs, and we enable zero-retention options where a provider offers them. Providers may keep non-content operational metadata such as token counts and latency.
The Agency Tier is your switch. Each manuscript has a tier you control. At T0 "No assistance" no AI feature can read that manuscript and nothing is sent to an AI provider for it.
4. Why we process your data, and on what basis
| Purpose | Data | Lawful basis (UK GDPR) |
|---|---|---|
| Providing the Service: the editor, import, export, Margin, Shepherd, consistency checks, certified exports, plan limits and allowances | Identity, account record, manuscript text, AI outputs, usage ledger, import previews | Performance of a contract with you (Article 6(1)(b)) |
| Billing: granting the plan you bought, showing your plan and renewal state | Billing link; Polar processes payment details as merchant of record | Performance of a contract (Article 6(1)(b)); Polar's own legal obligations for tax records |
| Security, abuse prevention and keeping the Service running: access control, the pilot password, rate limits, reconciling with Tiptap and Polar, diagnosing failures | Identity, account record, operational logs, operational evidence, usage ledger | Legitimate interests (Article 6(1)(f)) in operating a secure and reliable service. Logs exclude prose and identifiers by design, so the intrusion is minimal |
| Recording your acceptance of the Terms and answering rights requests | Account record | Legal obligation (Article 6(1)(c)) and legitimate interests in evidencing the agreement |
| Deciding where the Service is available and refusing use from comprehensively sanctioned countries: the country of your connection on each request, reported by Cloudflare, and your recorded home country | Home country; the connection country is checked and not stored except as the home country on first acceptance | Legal obligation (Article 6(1)(c)) under UK and US sanctions law for the refusal; performance of a contract (Article 6(1)(b)) for eligibility, since the Terms offer the Service in the United Kingdom and the United States |
| Reviewing Shepherd questions and answers to improve the Service: people read a question, the answer and the excerpts it cited, and adjust our prompts, retrieval and evaluation material by hand | Shepherd questions and answers | Legitimate interests (Article 6(1)(f)) in improving how the Service answers. You may object at any time; see below |
| Measuring which of our ads and links lead to sign-ups, so that we spend on the ones that work | Sign-up campaign | Legitimate interests (Article 6(1)(f)) in knowing which of our marketing works. The tags are recorded once, when your account is created, and are not shared with anyone, advertisers included. You may object; see below |
| Reading your feedback | The message, not retained | Legitimate interests (Article 6(1)(f)) |
| Sending The Prosa Letter to writers who asked for it | The Prosa Letter (optional); your email address and plan | Consent (Article 6(1)(a)), as regulation 22 of the Privacy and Electronic Communications Regulations requires for marketing email, given by ticking the box or turning on the switch and withdrawable by the link in every letter or the switch in Settings |
| Reporting daily to our own staff how the Service is used and where it fails | Internal reports | Legitimate interests (Article 6(1)(f)) in running and fixing the Service. The reports go only to named Thornwick Studios staff |
| Seeing which parts of the Service are used and where it fails, so that we can fix defects and decide what to build | Usage counts (every account) | Legitimate interests (Article 6(1)(f)). The identifier rotates daily and is never linked to you, nothing is stored on your device, and only content-free events are sent. You may object; see below |
| Following one writer's journey and watching masked recordings of the interface, only while the switch in Settings is on | Analytics cookies and session recordings (optional) | Consent (Article 6(1)(a)), given by turning the switch on and withdrawable by turning it off |
The consent-based processing is the optional analytics cookies and session recording, and The Prosa Letter, above. The application itself shows no marketing; the sign-up campaign above only records which of our links brought you. Special-category data inside manuscripts is addressed in Section D1.3.
Objecting to the sign-up campaign. Email privacy@prosa.so from the address on your account and we will delete the campaign tags from your account.
Objecting to the usage counts. Because the cookieless identifier cannot be traced to an account, we cannot find and remove your past events. If you object, email privacy@prosa.so from the address on your account and we will stop the Service sending usage counts from your account from then on.
Review of Shepherd questions, and how to object. To improve how Shepherd answers, we may read questions writers have asked, the answers given and the excerpts cited. This is done by people, on a read-only basis from the same store that the deletion process covers, and never by adding your questions or text to logs. What we learn changes our prompts, our retrieval and our hand-built evaluation material; it is never used to train or fine-tune any model, so the no-training commitment in Section 3 is unaffected. You may object to this review at any time by emailing privacy@prosa.so from the address on your account. We will then exclude your account from review, and setting a manuscript's Agency Tier to T0 stops new questions being possible for that manuscript.
5. AI disclosure
- Which features send text. Import structure detection, Margin scene readings, Shepherd questions and consistency checks. Nothing else does. The editor, Word export and the certificate never send text to an AI provider.
- What is sent. Only the scene text or excerpts needed for the request. A Margin reading sends one scene of up to 10,000 words. A consistency check or Shepherd question sends the passages the request needs.
- Who receives it. OpenRouter together with the approved model hosts it routes to in the United States and the European Union, as listed in Sections 3 and 6.
- What comes back. Informational output for you to accept or dismiss: rosters, entities, answers, findings, proposed structure. The Service makes no decision about you with legal or similarly significant effect.
- Training. Not used for training by us or by any provider, as set out in Section 3. Human review of Shepherd questions and answers, described in Section 4, changes prompts and evaluation material by hand and does not feed your text into any model.
6. Who we share data with
We share personal data only with the processors below, each acting on our instructions under a data-processing agreement, and with authorities where Section 11 applies. We do not sell personal data and never have.
| Processor | Role | What it receives | Country |
|---|---|---|---|
| Render | Hosting for all of our services and our single database | Everything Thornwick Studios stores | Germany (Frankfurt) |
| Tiptap | Collaborative document server, version history, conversion of imported Word files | Full manuscript text | European Union |
| Clerk | Authentication, sessions, sign-in emails | Name, email address, credentials or Google identity. If you sign in with Google, we receive your name and email address from Google as your identity provider | United States |
| Polar | Merchant of record: checkout, invoices, tax, subscriptions, billing portal, billing emails | Billing identity and payment details | United States |
| OpenRouter, and the approved model hosts it routes to (listed in Section 3) | AI inference for every AI feature. Every request is restricted to approved hosts that neither train on nor retain inputs, and the host that answered is recorded | Scene text and excerpts when you use an AI feature | United States; hosts in the United States and the European Union |
| Resend | Sends The Prosa Letter and keeps its mailing list; delivers our internal reports to our own staff | For subscribers: email address, plan and whether you have unsubscribed. The content of internal reports (Section 2) | United States |
| Datadog | Logs, metrics, uptime checks | Sanitised operational events; the feedback event carries your user id | European Union |
| Cloudflare | DNS and the proxy in front of every public hostname; terminates encrypted connections at its edge and tells our servers which country each request comes from | All traffic to the Service in transit, including manuscript text as you type; connection metadata and IP addresses. Nothing is stored | Global edge, under Cloudflare's data-processing addendum, which incorporates the EU Standard Contractual Clauses with the UK Addendum |
| PostHog | Usage counts for every account in cookieless mode; analytics cookies and session recording for accounts that have switched it on; analytics for the Website after the banner | Content-free interface events; for accounts that switched it on, the same events linked to the account and masked session recordings. Never manuscript text or anything you type | Stored in the European Union; PostHog is a United States company and may access the data from there under the UK Extension to the Data Privacy Framework |
7. International transfers
We are established in the United Kingdom. Your data is stored in Germany and processed by the providers above in the European Union and the United States.
- United Kingdom to the European Union (Render, Tiptap, PostHog's and Datadog's data storage, and OpenRouter's European Union hosts Mistral AI and Nebius): under the UK's adequacy regulations for the European Economic Area.
- United Kingdom to the United States (Clerk, Polar, Resend, OpenRouter and its United States hosts, and PostHog's and Datadog's support and engineering access to data stored in their EU regions): under the UK-US Data Bridge where the provider is certified under the UK Extension to the EU-US Data Privacy Framework, and otherwise under the International Data Transfer Agreement or the UK Addendum to the EU Standard Contractual Clauses, with a transfer risk assessment where required.
You can ask privacy@prosa.so which mechanism applies to a given provider and for a copy of the relevant safeguard.
8. Retention and deletion
We keep each category for the period in Section 2. Only three periods run automatically: operational logs (15 days), operational evidence (30 days) and import previews (until expiry). Everything else stays for the life of your account, or until you ask us to delete it.
Deleting a manuscript or an account. The Service lets you archive manuscripts but does not yet let you delete them yourself. To delete your account and every manuscript in it, press "Request account deletion" under Privacy in Settings, or email privacy@prosa.so from the address on your account. A request made in Settings is recorded with the time you made it and taken up by a person at Thornwick Studios, who carries it out by hand and marks it complete; you see its state in Settings. We complete a verified deletion within 30 days across our own database, the manuscript store, the search and Margin data, the Tiptap document, the Clerk user, your entry on The Prosa Letter's mailing list and, if you have a subscription, the Polar customer. Logs expire on their own schedule. The recovery copy in your browser (Section 3) is on your device, out of our reach: it is removed when a different account signs in on that browser or when you clear the site's data. Certified-export snapshots are purged through an audited erasure that keeps only an erasure record with the certificate's identifiers, so a certificate you have already given to someone can still be recognised as ours.
Legal holds. Where the law requires us to keep particular records, or a legal preservation obligation applies, we keep only what the obligation covers, delete the rest, and tell you unless we are legally prevented from doing so.
9. Security
- All traffic is encrypted in transit.
- Data at rest in our database is encrypted by Render's managed Postgres.
- Our services use least-privilege credentials.
- Our logging format excludes prose, email addresses and manuscript identifiers by construction.
- Certificates are signed, and the verification keys are published so that anyone can check a certificate without contacting us.
- The Service may be placed behind a shared access password in addition to individual sign-in.
No system is perfectly secure. If we become aware of a breach affecting your personal data we will assess it and notify the Information Commissioner's Office within 72 hours where the law requires, and tell you without undue delay where the breach is likely to result in a high risk to you.
10. Children
The Service is not directed at anyone under 18 and we do not knowingly hold personal data about children. We do not verify age: the Service is a paid tool for writing long-form fiction, offers nothing that appeals to children, is behind sign-in and a shared access password, and we judge a warranty of age proportionate to that risk. We will review that judgement if we learn that children are reaching it. If you believe a child has an account, tell privacy@prosa.so and we will delete it.
11. Law enforcement and legal requests
We may disclose personal data, including manuscript text, in response to valid legal process such as a court order, warrant or subpoena, where we are legally required or permitted to. We will tell you about a request for your data unless the law prohibits it, and as soon as any prohibition lapses. A disclosure to a foreign authority may be an international transfer; we assess each request individually and rely on the applicable derogation, limited to what is strictly necessary.
12. Changes to this Policy
We may revise this Policy. A material revision is published here with a new version number, and notice is shown in the Service at least 14 days before it takes effect. When a revision changes the acceptance key shown at the top of this page, the Service will ask you to accept it again before you continue. We keep a version history at the end of this page.
13. Contact and complaints
Email privacy@prosa.so, or write to Thornwick Studios Limited, Unit 13 Freeland Park, Wareham Road, Lytchett Matravers, Poole, BH16 6FA, England. We answer rights requests within one month. If you are not satisfied you may complain to a supervisory authority: in the United Kingdom, the Information Commissioner's Office at ico.org.uk or on 0303 123 1113; in the United States, your state attorney general, as the addenda describe.
Part B: Your rights
You have the right to ask for a copy of your personal data, to have inaccurate data corrected, to have data deleted, to restrict or object to processing, to receive data you gave us in a machine-readable format, and not to be subject to a decision based solely on automated processing that produces legal or similarly significant effects. The Service makes no such decision.
How to exercise them. For a copy of your data or deletion of your account, press "Request data copy" or "Request account deletion" under Privacy in Settings, or email privacy@prosa.so from the address on your account. A request made in Settings is recorded with the time you made it and taken up by a person at Thornwick Studios, who fulfils it by hand; Settings shows whether it is pending or complete. For every other right, email privacy@prosa.so. We verify identity by the signed-in account or the registered email address. We respond within one month, or tell you within that month if a complex request needs longer.
What a data copy contains. Your manuscripts are yours to export at any time from the Service, as a Word document per draft or as a certified plain-text export. On request we also supply your account record, usage ledger, AI outputs and Shepherd questions and answers in a machine-readable format.
The addenda in Part D set out the additional detail required by UK and US law.
Part C: The marketing website, prosa.so
This Part covers visits to prosa.so, including the blog and press pages. It does not cover the application, which Parts A and B cover.
What we collect. Nothing, unless you accept the cookie banner, which asks about analytics and advertising separately. If you accept analytics, PostHog records page views, referrer, device and browser information, page-performance metrics and a session replay with text inputs masked, under a pseudonymous identifier. PostHog is configured in its European Union region. If you accept advertising, the Meta Pixel sends Meta Platforms Ireland Limited ("Meta") that you visited, with the page address, the page you came from, your browser and device type and your IP address, and the first click on a link to sign up for the application on that page, together with the identifiers the Cookie Policy lists; if you are signed in to Facebook or Instagram in the same browser, Meta can link this to your Meta account. When you follow a link from the site into the application, or to another of the site's pages, the campaign tags the page was opened with (the utm_ tags in its address, which name an ad or post, not you) go with the link, whatever you chose in the banner, because they are part of the address and nothing is stored in your browser; if you then create an account, they are kept with it as Part A, Section 2 describes. Cloudflare, which proxies the site, sees connection metadata and your IP address as a matter of serving the page. If you email us, we hold your message for as long as needed to deal with it.
Basis and purpose. Analytics and advertising each run only on your consent, given separately through the banner and withdrawable at any time from "Cookie settings" in the footer. Advertising is used to measure which of our Facebook and Instagram ads lead people to Prosa and to let Meta show those ads to people more likely to be interested. The Meta Pixel never loads while your browser sends the Global Privacy Control signal, and it does not run in the application. Serving the site through Cloudflare, and answering your email, rest on our legitimate interests in running and supporting the site.
Meta. For the Meta Pixel, we and Meta are joint controllers for collecting your information on prosa.so and transmitting it to Meta, under Meta's Business Tools Terms and its Controller Addendum, which give Meta responsibility for answering requests about the data it holds. Once Meta has received the data it is the sole controller and uses it under its own Privacy Policy, which may include improving its advertising products. Meta may transfer the data to Meta Platforms, Inc. in the United States, which is certified under the EU-US Data Privacy Framework and its UK Extension.
Retention. PostHog keeps analytics data under its own retention settings for the project. Meta's identifiers stay in your browser for up to 90 days, as the Cookie Policy lists, and Meta keeps what it receives under its own retention. Your consent choices are stored in your browser until you clear them.
Rights. The rights in Part B apply. Analytics data is pseudonymous; to act on it we will need the identifier stored in your browser, which the Cookie Policy explains how to find. For data Meta holds, you can also use the controls in your Facebook or Instagram settings or Meta's own privacy request forms.
The Cookie Policy lists what the site stores in your browser.
Part D: Jurisdiction-specific addenda
Addendum 1: United Kingdom
This Addendum applies if you are in the United Kingdom. It supplements Parts A to C with what the UK GDPR and the Data Protection Act 2018 require.
D1.1 Controller
Thornwick Studios Limited, company number 16682779, Unit 13 Freeland Park, Wareham Road, Lytchett Matravers, Poole, BH16 6FA, England.
D1.2 Lawful bases
Section 4 sets out the lawful basis for each purpose. Where we rely on legitimate interests we balance that interest against your rights and freedoms before we start, and you may ask us at privacy@prosa.so how we reached the balance for any purpose.
D1.3 Special-category data in manuscripts
A manuscript may reveal special-category data, within Article 9 of the UK GDPR, about you or about other people, real or fictional. We do not ask for it and do not use it for anything other than the features you run. We process the content of your manuscript at your direction under our contract with you. Where Article 9 applies to the AI features, we rely on your explicit consent, given per manuscript through the Agency Tier control: the tier is T0 until you choose otherwise, the control explains that raising it lets the named AI features read that manuscript, and no text reaches an AI provider until you have raised it. You may withdraw that consent at any time by setting the manuscript's Agency Tier to T0, which stops every AI feature reading it, or by asking us to delete the manuscript. Withdrawal does not affect processing already carried out. We do not use such data for profiling, marketing or any purpose unrelated to the Service.
D1.4 International transfers
Section 7 describes the mechanisms. You may request a copy of the relevant safeguard from privacy@prosa.so.
D1.5 Processors
Section 6 lists our processors. Each acts only on our documented instructions under an agreement meeting Article 28 of the UK GDPR.
D1.6 Your rights
Under the UK GDPR you have the rights of access, rectification, erasure, restriction, data portability and objection, the right to withdraw consent where processing rests on consent, and rights in relation to automated decision-making. Part B explains how to exercise them. We respond within one month, extendable by two further months for complex requests, in which case we tell you within the first month.
D1.7 Complaints
You may complain to us first by emailing privacy@prosa.so with "Complaint" in the subject line; we acknowledge complaints within 30 days and tell you the outcome without undue delay. You may also complain, at any time, to the Information Commissioner's Office at ico.org.uk or on 0303 123 1113.
Addendum 2: United States
This Addendum applies if you are a resident of the United States. It supplements Parts A to C with what applicable state privacy laws require, including the California Consumer Privacy Act as amended by the California Privacy Rights Act (the "CCPA"), the Texas Data Privacy and Security Act and similar laws. Several of these laws apply only to businesses above a revenue or volume threshold that we may not meet; we offer the rights below to every US resident regardless.
D2.1 Categories, purposes and retention
| Category | Business purpose | Sold or shared? | Retention |
|---|---|---|---|
| Identifiers (name, email, user id, Polar customer id) | Providing the Service, billing, security | No | Life of the account |
| Manuscript text, AI outputs, and Shepherd questions and answers | Providing the features you run; human review of Shepherd questions to improve the Service | No | Life of the account, or until the manuscript is deleted |
| Commercial information (plan, subscription state, usage ledger) | Billing, allowances, security | No | Life of the account |
| Sign-up campaign (the campaign tags of the link you signed up from) | Measuring which of our ads and links lead to sign-ups | No | Life of the account |
| Marketing preferences (whether you subscribed to The Prosa Letter and each choice you made) | Sending The Prosa Letter, only with your opt-in | No | Life of the account |
| Payment information | Processed by Polar as merchant of record | No | Polar's retention |
| Internet activity (operational logs and evidence) | Security and reliability | No | 15 and 30 days respectively |
| Internet activity (cookieless usage counts) | Understanding use of the Service; not attributable to you | No | PostHog's project retention |
| Internet activity (analytics cookies and masked session recordings) | Understanding use of the Service, only with your opt-in | No | Life of the account, or until you opt out and ask for deletion |
| Sensitive personal information inside manuscripts | Providing the features you run, only | No | As manuscript text |
| Internet activity on prosa.so (your visit and clicks into the application, through the Meta Pixel) | Measuring our Facebook and Instagram ads and letting Meta show them to interested people, only with your opt-in on prosa.so | Shared with Meta for cross-context behavioural advertising, only with your opt-in | Meta's identifiers up to 90 days in your browser; Meta's retention for what it receives |
Apart from the Meta Pixel on prosa.so, we have never sold or shared personal information as the CCPA defines those terms, including in the preceding 12 months. The Meta Pixel runs only if you accept advertising in the cookie banner, never while your browser sends the Global Privacy Control signal, and never in the application; nothing the application holds is shared with advertisers. Thornwick Studios is below every threshold at which the CCPA applies to a business (annual revenue, number of consumers, and revenue from selling personal information), so the CCPA's "Do Not Sell or Share" requirement does not apply to us; we offer the rights below to every US resident regardless, and we show a short notice of what we collect and why when you create an account and, on prosa.so, in the cookie banner, with a link to this Policy.
D2.2 Sensitive personal information
A manuscript may contain sensitive personal information as state law defines it. We use it only to provide the features you run on that manuscript and for no other purpose, which is use necessary to perform the service you requested and so within the purposes for which the CPRA does not require a "Limit the Use of My Sensitive Personal Information" control. You may limit that use at any time by setting the manuscript's Agency Tier to T0, which stops every AI feature reading it, or by asking us to delete the manuscript.
D2.3 Automated decision-making
The Service produces informational output for your consideration. It makes no decision that produces legal or similarly significant effects on you, and no profiling.
D2.4 Your rights
Depending on your state you may have the right to know what personal information we hold and to access it; to delete it; to correct it; to receive it in a portable format; to opt out of sale or sharing (we sell nothing, and the only sharing is the Meta Pixel on prosa.so, which runs only on your opt-in and stops when you choose "Analytics only" or "Decline" in "Cookie settings"); to limit the use of sensitive personal information; and not to be discriminated against for exercising a right. Not every right applies in every state.
Global Privacy Control and targeted advertising. We do not sell personal information, and nothing the application holds is used for targeted advertising. The only sharing for cross-context behavioural advertising is the Meta Pixel on prosa.so, which runs only on your opt-in. On prosa.so, a browser that sends the Global Privacy Control signal is treated as having declined both analytics and advertising: no banner is shown and nothing is set. You can still accept analytics from "Cookie settings", but advertising is not offered and the Meta Pixel never loads while the signal is on. We do no profiling that produces legal or similarly significant effects, so no opt-out from profiling is needed (Virginia, Colorado, Connecticut). Where a state (for example Texas) requires consent before sensitive data is processed, the manuscript's Agency Tier control described in D2.2 is that consent.
D2.5 How to exercise them and when we respond
You or your authorised agent may email privacy@prosa.so. We verify identity by the signed-in account or the registered email. We respond within 45 days, extendable by a further 45 days where reasonably necessary (15 days in Nebraska), in which case we tell you. If we decline a request we explain why, and you may appeal by emailing privacy@prosa.so with the subject "Privacy Rights Appeal". If you are not satisfied with the outcome you may contact your state attorney general: California at oag.ca.gov/privacy, Texas at texasattorneygeneral.gov, Nebraska at ago.nebraska.gov, or the equivalent office in your state.
D2.6 Cross-border transfers
Your data is stored in Germany and processed by our providers in the European Union and the United States, as Sections 6 and 7 describe. We apply appropriate safeguards to every transfer.
D2.7 Contact
privacy@prosa.so, or Thornwick Studios Limited, Unit 13 Freeland Park, Wareham Road, Lytchett Matravers, Poole, BH16 6FA, England.
Version history
- 1.3.0, 11 October 2026. The Prosa Letter, our first marketing email: sent only to writers who ask for it, on consent given by an unticked box when accepting the Terms or a switch under Privacy in Settings, with an unsubscribe link in every letter that also turns the switch off. Each choice is recorded. Resend is named as the provider that keeps the mailing list and sends the letter, in the United States; letters carry no tracking pixel and no click tracking. Resend is also named as the provider that delivers the daily internal report on use and failures to our own staff, and the report's contents are listed. Deleting an account now also removes it from the mailing list.
- 1.2.1, 4 October 2026. The campaign tags a page of prosa.so was opened with also go with links to the site's other pages, so they are still there if you read another page before signing up. They remain part of the page address only; nothing is stored on your device.
- 1.2.0, 2 October 2026. When an account is created from a link that carries campaign tags, such as one of our ads, the tags are kept with the account so we can count sign-ups per ad, on legitimate interests with a right to object. The website passes its own tags into links to the application. Nothing is stored on your device for this, and the tags are not shared with advertisers. On prosa.so, the Meta Pixel now sends Meta only the first click on a sign-up link on a page, not every click into the application.
- 1.1.0, 1 October 2026. The website's cookie banner asks about advertising separately from analytics. If you accept advertising, the Meta Pixel sends Meta your visit and your clicks into the application so we can measure our Facebook and Instagram ads. Meta is named as joint controller for that collection and as sole controller afterwards, with its transfers to the United States. The US addendum records this as sharing for cross-context behavioural advertising, which runs only on your opt-in and never under Global Privacy Control. Nothing changes in the application.
- 1.0.4, 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.
- 1.0.3, 29 September 2026. The editor's recovery copy described: each manuscript you open is kept in your browser's storage on that device, including changes not yet saved to our servers, and stays after sign-out until a different account signs in there or you clear the site's data.
- 1.0.2, 25 September 2026. Datadog's logs, metrics and uptime checks are held in its European Union region, not the United States. Its support and engineering access from the United States is covered by the same safeguards as PostHog's. Operational logs are kept for 15 days, in production and staging alike, which is the retention Datadog offers.
- 1.0.1, 19 September 2026. TypeSafe AI added as an approved US inference host for matching Margin extractions to Story Bible entries. No-training and zero-retention routing controls apply.
- 1.0.0, 5 September 2026. First public-release policy, rewritten from the deployed system. Home country and the sanctions check added when the Service began applying them. Usage counts described as cookieless and anonymous for every account on legitimate interests, with a right to object; analytics cookies and masked session recording as opt-in through the Settings switch. Shepherd questions and answers named as their own category, kept with the manuscript, with human review to improve the Service disclosed under legitimate interests and a right to object. Cloudflare described as the proxy that handles traffic in transit. Complaints route added. The data-request controls in Settings described as notifying a person and showing their state; feedback described as going by email. OpenRouter routing described as restricted to an approved list of US and EU hosts, with the answering host recorded. Replaced category lists with the full inventory of what is held, where and for how long; added the description of where manuscript text goes and the named processors; corrected storage location to Germany; removed Stripe, usage analytics, device data, issue reports, the sign-up consent step and retention periods that were not enforced; rights now exercised by email; the marketing website is covered in Part C. Acceptance key
terms-2026-09. - 0.3.0, 3 June 2026. Company renamed to Thornwick Studios Limited.
- 0.2.0 and 0.1.0. Earlier application policy under the TrueTale name.