Free · No sign-up · Files never leave your device
Tools24 Lock PDF wraps your document in real, standards-based encryption — right inside your browser. Send it, store it, share it: only people with the password get past the cover page.
The tool
Choose a file, set a password, download the protected copy — about five seconds, start to finish.
Drag & Drop PDF Here
— or —
PDF up to 100 MB · your file never leaves this device
Browse your device or drag a file onto the panel.
You'll type it twice — the strength meter tells you when it's solid.
Share it freely — only people with the password can open it.
Processed on your device — nothing is uploaded, even on flaky Wi-Fi.
Ready to lock
This PDF will demand the password the moment anyone opens it — in Adobe Acrobat, macOS Preview, Chrome or on a phone.
Pick something only you — and whoever you allow — knows.
0% · preparing document
Your file now requires the password to open.
Keep this password safe — locked PDFs can't be recovered without it. There is no backdoor, by design.
Why Tools24
Most "free PDF lockers" upload your document to a server and hope you don't ask questions. Tools24 was built the other way around.
Your PDF is read, encrypted and rebuilt inside this browser tab. There is no server round-trip — pull the plug on your Wi-Fi after the page loads and it still works.
The PDF standard security handler with a 128-bit key — the same protection Adobe Acrobat applies. No preview, no thumbnail, not a single page renders without the password.
Opens exactly like any password-protected PDF you've received before.
No sign-up, no watermark stamped in the corner, no "3 files per day" counter. Lock one PDF or one hundred — the price is always the same: nothing.
Every feature on this page is free, forever.
The password requirement isn't a viewer preference — it's part of the file itself. It follows your PDF into email attachments, cloud drives, USB sticks and chat apps.
Privacy
We can't see your documents, and we couldn't hand them over if we wanted to — the encryption happens entirely on your device. Close the tab and the PDF is gone from memory. That's the whole policy.
FAQ
No. Tools24 Lock PDF runs entirely in your browser using a WebAssembly-powered PDF engine. Your document is read from disk, encrypted in memory and handed straight back to you — it never touches a network.
Real, standards-based PDF encryption — the standard security handler with a 128-bit key. When anyone tries to open the file, Acrobat, Preview, Chrome or their phone will ask for the password before a single page renders.
Technically 4 characters is the minimum, but we recommend 12 or more with a mix of letters, numbers and symbols. The built-in strength meter turns green when you're in a good place — and yes, case matters.
No — and that's exactly what you want from encryption. There is no backdoor, no reset link and no copy of your key anywhere. Store your password in a password manager before you lock anything important.
Yes. Open the locked file with its password, then use your reader's "Print to PDF" or "Export" to save an unprotected copy. The protection travels with the file, so it stays locked on every device until you unlock it.
Still stuck? or email us — we reply within a day.
No matches — try "password" or "privacy".