Encrypt files in your browser with AES-256
Lock a file behind a password using authenticated AES-256-GCM encryption that runs entirely on your device. The file never leaves your browser — there is no server to upload to.
Open this tool in FileX →How it works
- Open the Encrypt tool and drop in the file you want to protect.
- Choose a strong password. FileX derives a 256-bit key from it with PBKDF2-SHA256 at 250,000 iterations and a random salt.
- Download the encrypted
.filexcontainer (magicFLX1for a single file,FLX2for an archive of several). - Share the container over any channel; send the password separately. Only someone with the password can open it.
Why encrypt files locally instead of in the cloud
Most "secure" file services encrypt after your file reaches their servers, which means the plaintext still travels the internet and sits on someone else's disk. FileX encrypts before anything leaves your machine using the browser's built-in Web Crypto API. No upload, no account, nothing to breach.
What is a .filex file
A .filex container holds a 4-byte magic header, a random 16-byte salt, a random 12-byte IV, and the AES-256-GCM ciphertext. The GCM authentication tag means any tampering — or a wrong password — is rejected on decrypt rather than silently returning garbage.
Frequently asked questions
Is my file uploaded anywhere?
No. All encryption happens in your browser via the Web Crypto API. The live monitor at the bottom of the page shows 0 bytes uploaded, and the strict Content-Security-Policy blocks any third-party request.
What encryption does FileX use?
AES-256-GCM (authenticated encryption) with a key derived from your password using PBKDF2-SHA256 at 250,000 iterations and a random per-file salt. It is a standard, audited primitive — no hand-rolled crypto.
What happens if I forget the password?
The file cannot be recovered. There is no backdoor, no reset, and no copy of your key anywhere — that is the point. Store the password in a password manager.