The short version
Letterknife is an AI assistant that works on your email. To do that job it needs to read your mail — so this policy is blunt about what we access, where it goes, and what we never do with it. We don't sell data, we don't run ads, we don't train AI models on your mail, and no human reads your email.
Who we are
Letterknife is operated by Kremsa Digital (BYKD), based in the Slovak Republic, and is the data controller for your account data. Contact: hello@letterknife.com.
What we collect, and why
- Account basics. When you sign up with Google we receive your name, email address, and profile picture. That's all — signup alone grants no access to your mailbox.
- Gmail access, only if you connect it. Connecting a mailbox is a separate, explicit step with its own Google consent. It grants Letterknife the
gmail.modify scope, which the assistant uses to read messages, apply labels, archive, and create drafts in that mailbox. You can connect several mailboxes; each has its own grant. - What the assistant produces. Scanning your mail produces scores, summaries, briefs, and task-like records. These derived records are stored so the product works between sessions.
- Billing. Payments are processed by Stripe. We never see or store your card number.
Where your data lives
- Your email stays in Gmail. We do not copy your mailbox to our servers. The assistant reads messages through the Gmail API when it works and stores only the derived records described above.
- Gmail refresh tokens are stored encrypted in our Cloudflare infrastructure and are used solely to access the mailboxes you connected.
- Derived records and account data are stored with our database providers (Cloudflare, Supabase), isolated per user.
- AI processing uses Anthropic's API. Message content sent for processing is handled under Anthropic's commercial API terms, which do not permit training on customer content. Processing is transient — the AI provider is a processor, not a store.
Google API Services — Limited Use
Letterknife' use and transfer of information received from Google APIs adheres to the Google API Services User Data Policy, including the Limited Use requirements. In plain terms: Gmail data is used only to provide the assistant features you see, is never sold, is never used for advertising, and is never used to train generalized AI models. Humans do not read your Gmail data except with your explicit permission for support, when required by law, or for security abuse investigation.
What we never do
- No selling or renting data — to anyone, in any form.
- No advertising, no ad profiling, no third-party trackers on your data.
- No training of AI models on your email content.
- No human review of your mail, except the narrow cases listed above.
Disconnecting and deleting
- Disconnect a mailbox any time from the dashboard. We delete our copy of that mailbox's token immediately and stop all access. You can also revoke Letterknife' access from your Google Account permissions at any time.
- Delete your account by emailing hello@letterknife.com — we delete your account data, tokens, and derived records within 30 days, except what we must keep for legal or accounting reasons (e.g., invoices).
Your rights
If you're in the EU/EEA (and in most other places), you have the right to access, correct, export, restrict, or delete your personal data, and to object to processing. Email hello@letterknife.com and we'll handle it. You can also complain to your local data protection authority.
Processors we rely on
Google (Gmail API, sign-in), Cloudflare (hosting, storage), Supabase (database), Anthropic (AI processing), Stripe (payments), Resend (transactional email). Some processors are in the United States; transfers rely on standard contractual clauses and the EU–US Data Privacy Framework where applicable.
Cookies
We use session cookies to keep you signed in. No advertising or cross-site tracking cookies.
Changes
If this policy changes in a way that matters, we'll email account holders before the change takes effect. The date at the top always reflects the current version.