Use SecretPNG offline
Install the app once, then run core local tools with your network disconnected. This is the strongest way to be sure nothing leaves your device.
Install as an app (PWA)
Installs the tools to your device using your browser. On Chrome and Edge, use the button below or the install icon in the address bar. On iOS Safari, use Share → “Add to Home Screen”.
If your browser supports installation, use the install icon in the address bar, or your browser menu's “Install app” / “Add to Home Screen”. Meanwhile you can open the tools in your browser.
What works offline
- Encrypt a file
- Decrypt a file
- Create an encrypted vault
- Open an encrypted vault
- Password generator
- Passphrase generator
- File hash generator & verifier
- Recovery-code sheet
- Local private notes
Secret links and the contact form need a connection (they talk to a server by design) and are not part of the offline app.
Hosted version vs. offline version
The hosted website always runs the latest code, but you trust the JavaScript we serve each time you load it. The offline app caches a known version on your device, turning that into a one-time trust decision — nothing new is fetched while you use it offline.
How to verify what you installed
Each release lists file checksums in the changelog and the repository's release/ manifest (generated by npm run generate:checksums). You can compare the checksum of a downloaded offline bundle against the published value using the checksum verifier.
How updates work
When you open the installed app online, it checks for a newer version in the background and updates on the next launch. Running an outdated version of cryptographic software is a risk — old bugs stay unpatched — so reconnect periodically to update.
How to remove it
Uninstall it like any installed app (or, in your browser's site settings, remove the app and clear site data for secretpng.com). Clearing site data also deletes any local private notes stored in this browser, so export an encrypted backup first.