Free tool · Optimize & Repair
Repair PDF
Repair damaged or corrupted PDF files.
Fix PDFs that fail to open, display errors in other applications, or have structural issues from incomplete downloads. The tool uses pdf-lib's tolerant parser to read as much of the file as possible and rebuild a clean, valid PDF from the recovered content. Useful for files that were truncated mid-download, corrupted by a storage error, or generated by non-compliant software.
- Files never leave your device
- Runs entirely in your browser
- Free, no account needed
How to use Repair PDF
Two steps, and nothing to install.
Drop the damaged file
Add the PDF that will not open or throws an error. If it is encrypted, supply the password, since content that cannot be read cannot be repaired.
Download the rebuilt file
Whatever could be recovered is written into a clean, valid PDF and offered for download.
More free tools
Free, private, and no sign-up on any of them.
How this works in your browser
A PDF ends with a cross-reference table, essentially an index recording the byte offset of every object in the file. Most corruption damages that index rather than the page content itself, which is why a file can be unopenable while the pages inside are perfectly intact. The tool parses the document with a deliberately tolerant reader that scans for objects directly instead of trusting the index, then uses pdf-lib to write a brand new document from whatever it successfully recovered, generating a correct index as it goes. This explains both the successes and the limits: a broken index, malformed trailer or truncated tail is very recoverable, whereas page content that was itself overwritten is simply gone and no tool can rebuild it.
Repair PDF vs. upload-based online tools
| Feature | Repair PDF (in-browser) | Upload-based online tools |
|---|---|---|
| File upload required | No - never leaves your device | Yes - file is sent to a server |
| Processing queue | None - starts instantly | Often, especially at peak times |
| Watermark on output | Never | Common on free plans |
| Usage limits | None - free, unlimited use | Often capped per day or file size |
| Works offline once loaded | Yes, for most tools | No - requires a live connection |
| Account required | No | Often, for anything beyond a trial |
Common ways to use Repair PDF
Rescuing an interrupted download
Recover a PDF that was cut off mid-transfer and now refuses to open.
Fixing files from non-compliant software
Clean up PDFs generated by tools that write slightly invalid structure, so stricter applications will accept them.
Making a file usable by other tools
Rebuild a damaged document so it can be merged, split or converted, since most tools reject a malformed PDF outright.
Frequently asked questions
What it can and cannot do, and what happens to your files.
What kinds of damage can be repaired?
Mild structural issues such as missing cross-reference tables, malformed object streams, and truncated trailers are usually fixable. Severely corrupted files where page content itself is destroyed may not be recoverable.
Can it repair an encrypted or password-protected PDF?
Only if you supply the password. Encrypted files whose password is unknown cannot be repaired because the content cannot be read.
What if the repair does not fully work?
The tool recovers as much as possible. If pages are still missing or garbled, the underlying data may be too damaged. Try the Compress tool as an alternative - it re-writes the PDF structure which sometimes resolves minor issues.
Why do some PDFs open in one program but not another?
Because readers differ in how forgiving they are. Chrome and many viewers will quietly work around a broken index, while stricter software refuses the file outright. A PDF that opens in your browser but not in your editor is usually structurally damaged rather than fine, and rebuilding it makes it acceptable everywhere.
Can it recover a file that downloaded only partway?
Often, yes. A truncated download typically loses the index at the end of the file while the page data earlier in it survives. Rebuilding recovers whatever pages made it across, though anything genuinely never downloaded cannot be conjured back.
Will repairing change how my document looks?
No. Recovered pages are copied across as they are, so text, fonts and images are unchanged. Only the file structure around them is rewritten.
Is my file uploaded anywhere?
No. The rebuild happens inside your browser tab.
Recover your damaged PDF - free, runs entirely in your browser.
Files never leave your device. No upload, no account, and free for unlimited use.