Password-Protected PDF Won't Compress?
Here's the Fix
You tried to compress a PDF and got an error like "This PDF is password-protected." This is one of the most common compression failures, and it has a simple, safe fix — as long as you know the password.
Why Password-Protected PDFs Can't Be Compressed
Compression works by reading each page of your PDF, rendering it visually, and rebuilding a new compressed file from that. When a PDF is password-protected (encrypted), the page content is scrambled at the file level — no tool, including ShrinkPDF, can read or render the pages without first decrypting the file. This isn't a limitation specific to ShrinkPDF; it's true of virtually every PDF compression tool, because encryption is specifically designed to prevent unauthorised reading of the content.
If you see "This PDF is password-protected. Please remove the password first," that's the tool correctly detecting encryption and stopping rather than failing silently. The fix is straightforward: remove the password (if you have it), then compress normally.
Two Types of PDF Password
| Password Type | What It Does | Affects Compression? |
|---|---|---|
| Open password (User password) | Required to open and view the PDF at all | Yes — must be removed before compressing |
| Permissions password (Owner password) | Restricts printing, copying, or editing — but the PDF opens without a password | Sometimes — depends on whether the restriction blocks content extraction |
If you can open the PDF without entering anything, but get a compression error, you likely have an owner/permissions password. If you need to type a password just to view the PDF in the first place, you have a user/open password — this always needs to be removed first.
🗜️ Compress After Removing the Password
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Compress PDF Free →Remove Password on Mac (Built-in, Free)
Open the PDF in Preview
Double-click the PDF — it opens in Preview by default on Mac. Enter the password when prompted to view it.
Export without a password
Go to File → Export As. In the export dialog, leave the "Encrypt" checkbox unchecked. Save as a new file.
Compress the new file
The exported file has no password. Upload it to ShrinkPDF and compress normally.
Remove Password on Windows
Windows doesn't have a built-in PDF password remover, but you can use a free PDF reader to do it:
Open the PDF in Microsoft Edge (built-in)
Right-click the PDF → Open with → Microsoft Edge. Enter the password to view it.
Print to PDF
Press Ctrl+P, choose "Save as PDF" or "Microsoft Print to PDF" as the printer, and save. This creates a new PDF without the password (and without permissions restrictions).
Compress the new file
The printed PDF has no password protection. Upload it to ShrinkPDF and compress.
This method re-renders the PDF through the print pipeline, which means text that was selectable before may not be after (depending on the source). For most use cases (removing a password to compress and submit), this doesn't matter — but if you need to preserve selectable text, look for a dedicated password removal tool instead.
Remove Password Online (When You Don't Have Mac/Windows Access)
If you're on a phone or Chromebook without access to the methods above, several reputable services offer free PDF password removal. Be cautious: only use this for documents you own or have explicit permission to modify, and prefer services with clear privacy policies since your file (and password) will be processed on their server.
After removing the password through any method, return to ShrinkPDF to compress — this step always runs locally in your browser regardless of how you removed the password.
After Removing the Password
Confirm the password is gone
Close and reopen the new file. It should open without prompting for a password. If it still asks, you may have edited the wrong file or the export didn't apply.
Compress normally
Upload the password-free version to ShrinkPDF, choose your compression level, and compress. It will now process without the password error.
Decide if you need to re-add a password
If the original password protection was important for your use case (e.g., sending a sensitive document by email), you may want to re-apply a password to the compressed file after compression, using the same tool you used to remove it. This way the recipient still needs the password to open the smaller, compressed version.