Lock PDF

Secure your PDF.

Add a password to your confidential documents before sharing them. Secure local encryption using WebAssembly.

—Strong RC4 encryption

—Private password entry

—Works offline

—No account required

Don't trust us.
Verify it yourself.

Open DevTools → Network while converting. You'll see zero outbound requests. Every byte stays inside your browser tab.

—Works offline — no internet connection required

—Nothing is uploaded — ever

—Designed for sensitive documents

ZERO OUTBOUND CALLS

ElementsConsoleNetworkSources

FilterAll · XHR · JS · Wasm

NameStatusTypeSize

converter.worker.js200script48 kB

pdf.worker.wasm200wasm312 kB

✓ No requests to external servers

Powered byWebAssembly·Web Workers·pdf-lib·mammoth.js·Service WorkerAll open source · auditable in DevTools

How secure is the encryption?

We use standard PDF encryption that is compatible with all major PDF viewers like Adobe Acrobat.

Is my file uploaded to a server?

No. All processing happens entirely in your browser using WebAssembly. Your file never leaves your device.