Privacy Policy

1. Who we are

MendSage (“MendSage”, “we”, “us”, “our”) is a language-learning chat application operated by:

We are the data controller for the personal data described in this policy.

This policy explains what personal data we collect when you use the MendSage app and website, why we process it, who we share it with, how long we keep it, and the rights you have over it.

2. Who can use MendSage

MendSage is intended for users aged 16 and over. We do not knowingly collect personal data from anyone under 16. If you believe a child under 16 has provided us with personal data, contact us at [email protected] and we will delete it.

3. The data we collect

We do not collect your location, contacts, photos, or financial information. We show no advertising and we do not track you across other apps or websites.

3.1 Information you give us

Automated systems process your messages to provide the app's features (for example, generating corrections — see section 5). People on our team do not read the conversations you have with other members. The only times a person reviews a message are: (1) when you or another member reports it, in which case a copy of that message is reviewed by a human operator so we can act on the report (for example, removing the content or restricting the account responsible); and (2) the feedback and support messages you send us, which are read by our staff so we can reply to you and improve the app. When you submit feedback we also attach basic technical details (your app version, device platform, and app language) to help us diagnose the issue you report.

3.2 Information we generate about your use

3.3 Information we collect automatically

3.4 Payments

If you buy a subscription, the purchase is processed by Apple (App Store) or Google (Google Play) acting as the merchant of record. We do not receive or store your card or payment-account details — we receive only confirmation of your subscription status.

3.5 Sensitive information

MendSage does not ask for special-category data (such as health, religious, or political information). Because messages are free text, please do not include sensitive personal information in your messages — they are processed by our AI providers as described in section 5.

3.6 Stored on your device

A copy of your chat history is kept locally on your device so you retain your conversations even after we clear older messages from our servers. See section 8 for how long it is kept and section 10 for how it is protected.

4. Why we process your data, and our legal bases

Where we rely on legitimate interests, we have weighed those interests against your rights. You can object to that processing — see section 9.

5. How MendSage uses AI

MendSage uses AI in two ways: to correct your messages, and to power optional AI practice companions — automated characters you can chat with to practise when a real partner isn’t available. Both require sending text to a third-party AI provider, and we have designed this to share as little as possible:

What we send to the AI provider:

• the message text — the message to be corrected, or the message you send to a companion;
• a small amount of recent conversation context (recent prior messages in the same conversation), so the correction or reply makes sense in context;
• your target language, native language, and chosen explanation language, plus any clarification you provide.

To help an AI companion stay in context across a longer conversation, we may also send recent history to an AI provider to produce a short summary, which we store with your account (see sections 3.2 and 8).

What we do not send:

• your name, email address, or account identifiers. The request is pseudonymous — the provider receives message content, not who you are.

Please note: because recent conversation context is included, a correction request for one member can include recent messages written by other members of the same conversation.

Our AI providers and how long they keep it:

None of these providers uses your content to train their models. Because Mistral and the Google Cloud path both run in the EU, that processing does not involve a transfer outside the EU/UK. Anthropic’s and OpenAI’s first-party APIs use global routing, so a request routed to them may be processed outside the EU/UK (see section 7).

The providers listed above also generate AI companion replies, grammar and word explanation cards, and the conversation summaries described earlier; which provider handles a given request can vary with availability. The safeguards in this section — pseudonymity, no training on your content, and the retention limits above — apply equally to those requests.

Because messages are corrected and answered on our servers, MendSage is not end-to-end encrypted — our systems and our AI providers must be able to read message text in order to coach it and to power AI companions.

6. Who we share your data with

Within a conversation. The other members of a conversation can see the messages you send in it and the corrections attached to them, including any clarification questions and answers. That is how MendSage works as a shared practice space.

We do not sell your personal data. Beyond the members of your conversations, we share your data only with the service providers (“sub-processors”) that we rely on to run MendSage, each under a data-processing agreement:

We may also disclose data where required by law, to enforce our terms, or to protect the rights, safety, or property of MendSage or others.

7. Where your data is stored and international transfers

Your account and conversation data are stored in the European Union (Frankfurt).

Some processing involves transfers outside the EU/UK — specifically AI processing by Anthropic and OpenAI (whose first-party APIs use global routing and may process data in the United States or other regions) and app-store, payment, and notification services provided by Apple and Google in the United States. Our other AI providers — Mistral and Google Gemini on Google Cloud — run in the EU, so those paths do not involve a transfer outside the EU/UK. Where we transfer personal data to a country without a UK/EU adequacy decision, we rely on appropriate safeguards, such as the EU Standard Contractual Clauses and the UK International Data Transfer Addendum, and/or the providers’ certification under the EU–US Data Privacy Framework.

You can request a copy of the relevant safeguards by contacting us.

8. How long we keep your data

We keep your personal data for as long as your account is active. Specifically:

• Message bodies are automatically cleared 30 days after a message has been corrected — the message record remains (it anchors your learning history) but its text is removed.
• Corrections, vocabulary, profile, and account data are retained until you delete them or close your account. When you request account deletion (see section 9), your account enters a 14-day recovery period during which you can restore it by signing back in; after that window your data is permanently erased. Messages you sent in a conversation shared with someone else are anonymised rather than removed (the content is deleted and the message is re-labelled “Deleted account”) so the other member’s conversation history stays intact. Note that corrections include the corrected text and explanations that form your learning history, so some content derived from a message persists after that message’s body is cleared, until your account is erased.
• On your device: the app also keeps a copy of your chat history locally on your device, so you keep your conversations even after the server has cleared the 30-day-old bodies. This local copy stays on your device until you delete the app, delete your account, or clear your history; it is protected by your device’s built-in encryption (iOS Data Protection; Android file-based encryption).
• IP addresses used for rate-limiting are short-lived and cleared on a rolling basis.
• Install source is kept with your account. When your account is erased it is unlinked from you and remains only as anonymous campaign statistics.
• Feedback & support threads are kept for up to 12 months after the conversation is resolved, so we can maintain a support history and handle any follow-up, and are then deleted. If you delete your account, your feedback threads are removed with it.
• AI companion memory (the short conversation summaries) is kept while the companion conversation exists, and is deleted when you delete that conversation or your account.
• AI providers delete the content we send them within 30 days (section 5).
• Safety reports. When you or another member reports a message, we keep a copy of that message, along with the report and our review decision, as a record of a possible breach of our rules. These safety records are kept separately from your conversation and are not removed when the reported message is deleted or when an account is closed (when an account is erased we unlink the record from that account's identifiers). We retain them only as long as necessary for safety, to resolve disputes, and to comply with our legal obligations.

We may retain limited information for longer where we are legally required to, or to resolve disputes and enforce our agreements.

9. Your rights

Under UK and EU data protection law, you have the right to:

• access the personal data we hold about you;
• rectify inaccurate data;
• erase your data (“right to be forgotten”);
• restrict or object to certain processing;
• data portability — receive your data in a portable format;
• withdraw consent at any time, where we rely on consent.

You can edit your profile and delete your account and associated data directly in the app (Profile → Delete account). Deletion takes effect after a 14-day recovery period — sign back in during that window to cancel it. You can also request deletion via our account-deletion page or by contacting [email protected]. For any other request, contact us at the same address. We will respond within one month.

If you are unhappy with how we handle your data, you can complain to the UK Information Commissioner’s Office (ICO) at ico.org.uk, or to your local EU supervisory authority.

10. How we protect your data

• Your data is encrypted in transit between your device and our servers.
• Access to conversations is restricted, so you can only see the conversations you are a member of.
• Data stored by our hosting provider is encrypted at rest.
• Chat history cached on your device is protected by your device’s built-in encryption (iOS Data Protection; Android file-based encryption of app-private storage), readable only while your device is unlocked.
• Access to production systems is restricted and authenticated.

No service can guarantee absolute security, but we work to protect your data using appropriate technical and organisational measures.

11. Changes to this policy

We may update this policy from time to time. When we make material changes, we will update the “Last updated” date above and, where appropriate, notify you in the app.

12. Contact us

Questions about this policy or your data: