pdfcosmos

Change PDF Password

Swap a known PDF password for a new one, entirely in your browser.

Free, fast, and privacy-first.

Change your PDFs' password

or drag & drop files here

PDF files onlyup to 30 filesup to 100 MB each300 MB total

Change a PDF password — swap a known password for a new one

Changing a PDF's password replaces the password it has now with a new one in a single step: the file is opened with the current password, then immediately re-encrypted with the new one using AES-256, so it is never left unprotected in between. You do need to know the existing password — this opens and re-secures a file you already control; it can't crack or bypass a password you don't have. Think of it as Protect and Unlock combined, but safer than removing the old password and adding a new one as two separate operations.

You can update one PDF, or up to 30 that share the same current password, in one go — a single file downloads as a PDF, several as a ZIP, each re-encrypted with the new password. Everything runs in your browser through WebAssembly (qpdf), so your document and both passwords are processed on your device and never leave it. To add a first password to an unprotected file use Protect PDF; to remove a known password entirely use Unlock PDF.

  • Never left unprotected

    Decrypts with the old password and re-encrypts with the new one in a single pass.

  • Strong AES-256

    The new password uses AES-256 encryption, the same standard as Protect PDF.

  • Change up to 30 at once

    Update many files that share the current password; they download together as a ZIP.

  • Passwords stay on your device

    qpdf runs in your browser. Your file and both passwords never leave it.

How to change a PDF's password

  1. Add your PDF(s)

    Drop one (or up to 30) password-protected files into the upload area.

  2. Enter the current and new password

    Type the password the file has now, then the new password (twice). They never leave your device.

  3. Download

    Click the button to re-encrypt with the new password, then download the PDF (a ZIP for several).

Frequently asked questions

Are my PDF or passwords sent to a server?
No. The whole change runs in your browser using WebAssembly (qpdf). Your file and both passwords never leave your device. You can confirm it in your browser's Network tab: no data is sent.
Do I need the current password?
Yes. To change a PDF's password you must know the current one. It's used to open the file before re-encrypting it with the new password. This can't crack or bypass a password you don't have.
How is this different from Protect and Unlock?
It's both in one step. Protect PDF adds a password to an unprotected file. Unlock PDF removes a known password. Change PDF Password swaps a known password for a new one, decrypting with the old and re-encrypting with the new, so the file is never left unprotected in between.
What encryption does it use?
AES-256, the same as Protect PDF. Anyone opening the file afterwards needs the new password you set.
Can I change the password on several PDFs at once?
Yes. Add up to 30 PDFs that share the same current password. One file downloads as a PDF, and two or more download together as a single ZIP, all re-encrypted with the new password.