The short version
Your export file is parsed in your browser. Pattern stats (who texts more, reply gaps, conflict phrases, etc.) are computed locallyand are not sent to AI. Optional Q&A sends a limited excerpt of recent messages plus summary statistics — only when you sign in and ask.
What stays on your device
- The export file (.txt, .json, or .zip) — read and parsed in JavaScript in your browser. We do not upload the file to parse it.
- Thread insights — balance, initiation, reply speed, repair language, late-night volume, and the rest of the insight cards.
- Saved threads — stored in this browser's
localStorage(trimmed by tier so storage does not blow up). Another device or a cleared browser will not have them unless you re-import.
You can import and explore insights without creating an account.
What optional AI sends (only if you ask)
If you sign in and submit a question, your browser calls our API on Vercel. That request includes:
- Your question (what you typed)
- Summary statistics computed over the full thread (counts, percentages, patterns — not every message verbatim)
- A capped slice of recent messages for conversational context (not your entire export)
The server forwards that payload to an AI provider configured in our deployment (e.g. Azure OpenAI or xAI). We do not store your full chat history on our servers.
Free accounts: 30 AI questions per UTC day. Premium unlocks higher limits and larger imports — see pricing.
What we store when you sign in
- Email and auth identity (via Supabase)
- Premium status and daily AI question count (for rate limits)
We do not persist your full message export in our database as part of the normal product flow.
What we do not do
- Sell your chat data
- Train models on your exports
- Require an account to see local pattern stats
- Parse exports on a server by default
Your choices
- Use insights only — no AI, no sign-in required for import + stats
- Clear site data in your browser to remove saved threads
- Do not use AI if you do not want any message text sent to a model
ThreadLens is a reflection tool, not therapy, legal advice, or a way to win arguments. If you are in an unsafe situation, talk to someone you trust or a professional — not an app.