How to Password Protect a PDF Without Adobe (5 Free Ways Tested)

Last tested: October 2026. I ran the LibreOffice method end-to-end on a real sample PDF and verified the encryption held; every other method below was cross-checked step-by-step against the vendor’s current documentation.

Adobe Acrobat is the obvious way to lock a PDF, but it is far from the only one — and it is not free. You can password protect a PDF without Adobe using tools that cost nothing: an online encryptor, a free Windows desktop app, or the office suite you may already have installed.

The short answer: the fastest free way is PDF24’s online Protect PDF tool — upload the file, set a password, download the encrypted copy in under a minute, no install and no account. If the document is sensitive and you do not want to upload it anywhere, use LibreOffice (File > Export As > Export as PDF > Security) or PDF24 Creator on Windows instead — both encrypt fully offline.

What does password-protecting a PDF actually do?

PDF security has two different passwords, and confusing them is the most common mistake:

User password (password to open). This encrypts the file. Nobody can open the document at all without it. This is the password you want for confidential files.

Owner password (permissions password). This controls what people can do after opening the file — printing, copying text, editing. Anyone can still read the document; they just face restrictions. Treat these restrictions as a polite request, not security: many PDF tools ignore them entirely.

The rule of thumb: if confidentiality matters, always set a user password. A permissions-only password protects nothing against anyone determined.

Method 1: PDF24 Protect PDF online (fastest, no install)

PDF24’s free Protect PDF tool runs entirely in the browser. There is no account, no install, and the tool itself is free (PDF24 funds it with advertising; its protect page carries a 4.9/5 rating from 758 user votes).

1. Open the PDF24 Protect PDF page and drop your PDF into the upload box.
2. Enter your password in the security settings. You can also set an owner password and restrict printing, copying, or editing.
3. Click the protect/encrypt button, then download the secured PDF.

Open the downloaded file in any PDF reader — it should ask for the password before showing a single page. PDF24 states that uploaded files are deleted from its servers after a short period, but as with any online tool, I would not upload tax returns or contracts containing account numbers. Use Method 2 or 4 for those.

Method 2: PDF24 Creator on Windows (free, fully offline)

If you are on Windows and want a permanent free tool, PDF24 Creator is the desktop sibling of the online tool — free, with no account, and everything happens on your PC so nothing is uploaded.

1. Install PDF24 Creator and open it via the PDF24 Launcher (the PDF Creator tab).
2. Drag your PDF into the program window.
3. Click the save button in the top-right of the document window and choose user-defined in the “select output profile” dialog.
4. Switch to the Security tab. Here you get four groups of settings: the password for encryption, the encryption depth (128 or 256 bit — pick 256), a separate password required to open the PDF, and access rights (printing, copying, editing).
5. Click Continue, choose where to save, and confirm the file type is PDF.

These steps follow PDF24’s current interface (verified against the vendor’s documentation, October 2026). The 256-bit option is the strongest setting the format offers here — there is no reason to pick 128-bit.

Method 3: Sejda Protect PDF online (no install, generous free limits)

Sejda’s Encrypt PDF tool is the best-known alternative to PDF24 online. Its free tier covers documents up to 200 pages or 50 MB with 3 tasks per hour, which is plenty for occasional use. Sejda states that uploaded files are automatically and permanently deleted after 2 hours.

1. Open Sejda’s Encrypt PDF page and click Upload PDF files (or drag the file in — Dropbox and Google Drive work too).
2. Choose a strong password — Sejda itself recommends 16 characters or more. You can optionally add an owner password for permission changes.
3. Pick optional restrictions (printing, copying, form filling, commenting).
4. Click Encrypt PDF, then Download.

I verified each step of this flow on Sejda’s current tool page (October 2026): the upload, the 16-character password recommendation, the optional owner password, and the restriction checkboxes all match what is described above. If your file is sensitive enough that “deleted after 2 hours” is not good enough, use an offline method instead.

Method 4: LibreOffice (free, offline, Windows/Mac/Linux)

This is my pick for sensitive documents, because the file never leaves your computer and the software is completely free and open source. The password option hides inside the PDF export dialog:

1. Open your document in LibreOffice Writer (or import the PDF — Writer can open many PDFs for re-export).
2. Go to File > Export As > Export as PDF.
3. In the PDF Options window, open the Security tab.
4. Click Set passwords: enter one password to open the file and, optionally, a second permissions password. You can then restrict printing, changes, and content copying.
5. Click Export and save.

Hands-on test: I ran this in LibreOffice 24.2.7.2 with a document-open password on a real test file. The exported PDF was encrypted, refused to open without the password, rejected a wrong password, and decrypted cleanly with the correct one (verified with pypdf). No Adobe, no upload, no cost. If you do not have LibreOffice yet, it is free from the official LibreOffice download page — and if you are weighing office suites, see the best free Microsoft Office alternatives I compared hands-on.

Method 5: Microsoft Word (if you already have Office)

If you have Word, you already own a PDF password tool — no new software needed. Microsoft’s own documentation confirms the steps (support.microsoft.com):

1. Open the document in Word (desktop app — Word for the web cannot add passwords).
2. Go to File > Save As and choose PDF as the file type.
3. Click Options in the save dialog and check Encrypt the document with a password (available in Word for Microsoft 365 on Windows).
4. Enter the password twice and save.

Two Microsoft-specific warnings worth knowing: Word document passwords are case-sensitive and capped at 15 characters, and Microsoft cannot recover a forgotten password for you — store it in a password manager before you close the file. Alternatively, encrypt the .docx first via File > Info > Protect Document > Encrypt with Password, which uses strong AES-256 encryption, and share that instead of a PDF.

Which free method should you pick?

Security reality check: a password is not magic

Three honest caveats before you trust a password with anything important:

Share the password separately. Emailing the locked PDF and its password in the same message defeats the purpose. Send the file one way (email) and the password another (a call, a messaging app, a password manager share).

Weak passwords fall fast. A short dictionary word on a PDF can be brute-forced in minutes by free tools. Use 16+ characters mixing upper/lowercase, numbers, and symbols — and generate it with a password manager rather than inventing one.

Permissions are not encryption. As noted above, an owner password that only restricts printing or copying is trivially stripped by many free tools. Real protection means a user password that encrypts the whole file.

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