There are two kinds of "password protected" PDF in the wild: files with real encryption, where the content is mathematically unreadable without the key — and files with a viewer-level nag that any competent tool ignores. If the document matters, you want the first kind, and it is worth two minutes to understand the difference.
What real PDF protection is
A properly protected PDF is encrypted with AES — the current standard is AES-256, the same algorithm used for banking and government traffic. The password is transformed into the decryption key; without it the file's content is noise, and no "recovery" service can help. This is what Acrobat applies, and it is what our tool applies too — the difference is where it happens.
The two-minute flow
- Open Protect PDF and drop the document.
- Type a password (twice). Use a real one — length beats cleverness; four random words beat "Summer2026!".
- Optionally untick "Allow printing" to restrict viewers even after they enter the password.
- Download the encrypted copy. Test it: the file should now demand the password on open.
qpdf — the standard PDF toolkit — runs in your browser. The file and password never leave your device.
Why browser-side matters more here than anywhere
Think about what an upload-based protect-PDF service holds after you use it: your confidential document, and the password you just chose for it — often the same password you use elsewhere. Even with the best intentions, that is a needless copy of exactly the wrong pair of things. When the encryption runs in your browser (you can switch off Wi-Fi after the page loads and it still works), the trust question never arises.
Removing a password you know
Locked PDFs are friction: they break previews and search, and some printers refuse them. Once a document no longer needs protecting, Unlock PDF takes the password you enter, decrypts on your device, and saves a copy that opens freely. What it will not do — what nothing can honestly do — is open a file whose password is lost. Pair protection with the rest of the private PDF workflow: sign, merge and compress, all without an upload.