Letterfork

Privacy Policy

Last updated: April 28, 2026

Letterfork is a tool that helps newsletter writers repurpose their issues into platform-native social posts. This page explains what data Letterfork collects, why, who else touches it, and how to get it deleted. Plain English, no dark patterns.

What we collect

  • Account details: email address, and (if you sign in with Google) the name and avatar your Google account exposes.
  • Voice Profile sources: the URLs or pasted text of your past newsletters that you submit to train your style profile.
  • Rewrite content: the newsletters you submit for rewriting (URL or pasted text), and the platform-native outputs we generate from them.
  • Custom prompts (Pro and Unlimited tiers): the instruction overlays you save in the Settings page.
  • Usage and billing: number of rewrites you've run, subscription tier, Stripe customer ID. We do not store your full card number — Stripe handles that.
  • Product analytics: anonymized event data via PostHog (page views, button clicks, funnel steps). No keystroke logging, no session replay of inputs.

How we use it

  • To generate rewrites — your newsletter is sent to language models so they can rewrite it in your voice for each platform.
  • To extract your voice profile from the newsletters you submit during onboarding (one-time analysis, stored as a text profile on your account).
  • To bill you, manage your subscription, and handle taxes.
  • To send transactional emails (welcome, account changes, first rewrite ready) and product emails (monthly recap, churn-risk check-ins, upgrade nudges). You can opt out of product emails from the Settings page.
  • To debug failures and improve Letterfork. We never sell your data, and we do not train AI models on your content.

Third parties that process your data

Letterfork is a small operation and uses well-known service providers for the heavy lifting. Each receives only the data it needs to do its job:

  • Supabase — Postgres database (account, voice profiles, rewrites) and authentication.
  • Anthropic — Claude Sonnet powers voice extraction and the main rewrite step. Anthropic does not train models on data sent through their API.
  • OpenAI — GPT-4o-mini handles cheap secondary tasks like length validation and quote extraction.
  • Stripe — payments, subscription state, customer portal.
  • Resend — transactional and product emails.
  • PostHog — product analytics.
  • Google — only if you choose Google sign-in, which uses Google OAuth.
  • Vercel — application hosting and edge delivery.

How long we keep it

We retain your data for as long as your account is active. If you delete your account, we remove your account record, voice profiles, rewrites, and custom prompts within 30 days. Stripe billing records may be retained longer where tax law requires.

Your rights

  • Export: request a copy of all your data — we'll send it as a JSON dump within 30 days.
  • Delete: request account deletion at any time.
  • Opt out of product emails from the Settings page. Transactional emails (account events, billing) cannot be opted out of while you have an active account.
  • Correct or update any of your account data via the Settings page or by contacting us.

For any of the above, email hi@letterfork.com from the email on your account. EU and California users have the same rights under GDPR and CCPA respectively.

Cookies

Letterfork uses two kinds of first-party cookies: a session cookie (Supabase auth) so you stay signed in, and an analytics cookie (PostHog) for funnel analysis. We do not use third-party advertising cookies.

Children

Letterfork is not intended for users under 13. If you believe a child has registered, contact us and we'll delete the account.

Changes

If we change this policy materially, we'll email registered users before the change takes effect. Minor edits (typo fixes, clearer language) won't trigger a notification.

Contact

Letterfork is operated by Super, a solo founder. hi@letterfork.com reaches a real person, not a ticketing queue.