Built to be checked.

How it’s protected

• End-to-end encrypted. Messages and files are locked on your device with AES-256-GCM. The key is in the part of the link after the #, which browsers never send to us.
• Quantum-resistant. Links use 256-bit keys. Requests and private replies combine a classic lock (P-256) with ML-KEM-768, the US government’s 2024 standard, so breaking them means breaking both.
• Rules enforced by our servers. One-time opens, expiry, and the three-try limits are enforced in a single database step, so two people opening a link at the same moment can’t both get it.
• Erased, not hidden. The encrypted message is deleted the moment it’s opened for the last time. Files are deleted as soon as the download finishes.
• Nothing from anywhere else. A strict browser security policy allows only our own code. No outside scripts, fonts, analytics, ads, or cookies.

The details are on How it works and Transparency.

Report a security problem

If you think you’ve found a weakness, please email hello@safewith.us with “Security” in the subject. Tell us what you found, how to reproduce it, and what it could affect. We’ll reply within 3 business days and keep you updated until it’s fixed.

Good-faith research is welcome. Please:

1. Use only your own links. Test with links and requests you created. Never try to open anyone else’s messages.
2. Keep the service running. No denial-of-service, spam, or automated floods.
3. Leave people out of it. No phishing or tricking our users, and no attacks on our providers.
4. Give us time. Allow 90 days for a fix before sharing details publicly.

If you follow these rules, we’ll treat your research as authorized and won’t take legal action over it. We don’t run a paid bug bounty yet, but we’re happy to thank you publicly if you’d like. Machine-readable details are at /.well-known/security.txt.

Check the code yourself

Below is every script our site runs in your browser, with its SHA-256 fingerprint. If even one character of a file changed, its fingerprint would be completely different. Check your browser’s copy right here, or check any file on your own computer:

These fingerprints show that the code reached you unchanged. They can’t show what the code does. If you’d like to review it, email us. The post-quantum code in /vendor/mlkem.js is the unmodified open-source @noble/post-quantum library, which we test against the US government’s official results.