Choose a file
The browser reads the selected file locally. Its bytes are not uploaded to this service.
Encrypt a file
Seal a file with a passphrase, or open one you were sent, in this browser.
The file stays on this device
Nothing is uploaded while you work. The download at the end is produced in your browser.
Encrypt
Seal a file
Any file type. Large files take longer because the work happens on your device.
Sealed file ready
Send the sealed file and give the password to the recipient through a different channel.
Decrypt
Open a sealed file
Choose a file that was sealed on this page.
What the password protects
The file is encrypted in this page with a key derived from your password. The sealed result is the only thing that leaves your device, so a mail provider, a chat service, or a courier sees a file it cannot read.
There is no recovery
The password is not stored, not transmitted, and not escrowed. If it is lost, the sealed file cannot be opened by us or by anyone else. Keep it in a password manager, and test the round trip once before you delete the original.
What encryption does not hide
The sealed file still shows its size and the time it was created, and the channel you send it through sees that a file was sent. Encryption protects the contents, not the fact that you sent something.
How it works
Seal it with a passphrase
A fresh salt and AES-256-GCM encryption create a protected file on this device.
Save the sealed copy
Download the result and send the passphrase through a separate channel. Lost passphrases cannot be recovered.
Is the file uploaded at any point?
No. The file is read by the page, encrypted on your device, and handed back to you as a download. There is no upload step in either direction.
Can I open the sealed file with another tool?
Use this page. The container format is specific to this tool, so other programs will not recognise it. That also means you should keep the tool available for as long as you keep the sealed file.
How large a file can I encrypt?
The limit is your device's memory, not a server rule. Files of a few hundred megabytes work on a desktop but can be slow on a phone, and the tab has to stay open until the download starts.