Password-Protect a File — and Let It Open Without Installing Anything

Email and chat were never built to carry private documents. File Lock encrypts a file with a password using AES-256, entirely in your browser, and hands you back something you can send anywhere. Pick the self-opening page and the recipient just has to double-click, enter the password, and get the file — no app, no account, nothing uploaded by either of you.

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The problem

The standard advice for sending something private is "zip it with a password", and that's exactly what every university IT page and government guide says. The problem is what happens next. You install 7-Zip or WinRAR, figure out which setting actually encrypts the contents and not just the filenames, and then discover the recipient has a phone, a Mac or a work laptop where they can't install anything. So the encrypted archive sits there unopened, and eventually you just send the document unprotected because the deadline is today. The alternative — uploading it to a file-sharing site that promises security — means trusting your private document to a company you've never met, just because the marketing page says so.

How File Lock works

• Drop in the file and choose a password. No good idea? Tap the generator — it makes an easy-to-read, sixteen-character key you can even read out over the phone.
• Choose how to send it: a self-opening page (.html) for anyone, or a smaller locked file (.enc) if the recipient will reopen it here.
• Save and send it as usual. Send the password separately — over a different app or by call. Anyone who gets a locked file from you can open it for free, forever.

What you get

• Real encryption, not a settingAES-256-GCM, with a key derived from your password via PBKDF2-SHA256 over 310,000 rounds — using the cryptography already built into your browser. The authentication tag means a tampered file refuses to open instead of opening wrong.
• They only need a browserThe self-opening version packs your encrypted data into a small page that can decrypt itself. Double-click, enter the password, and the original file comes out — on a phone, a Mac, a locked-down work laptop, even with no internet connection at all.
• Nothing gets uploaded, by either of youYour file is read, encrypted and saved entirely in your own browser. There's no server, no account and no analytics, and the page the recipient opens is just as offline as the one you locked the file in.
• Opening is always freeUnlocking never requires Pro, an account or a payment — not for you, and not for anyone you send a file to. Nobody should have to pay to access their own documents.

Private by design

File Lock has no server anything gets sent to. The password is never stored, never transmitted and never held on file — with one consequence worth stating plainly: nobody can recover it, not you, not us. Lose the password and the file is gone for good, so write it down somewhere safe before you send anything. The other honest point: the weak spot isn't the encryption, it's your password. Anyone who gets hold of the locked file can guess offline, on their own machine, as fast as their hardware allows, with nothing slowing them down. A short or common password falls to that; a long, unusual one doesn't. And send the password over a different channel than the file — sending both together by email is the same as sending the file unprotected.

Free vs Pro