Repair a damaged PDF that won't open
Drop in the broken file: its structure is rebuilt, the pages that can still be read are recovered, and you see exactly what was repaired.
- Free
- Truncated files accepted
- Repair report
- 100% private
100% private — Everything is processed directly in your browser: your files, voice, and image are never sent to Chatzam's servers.
How to repair a corrupted PDF
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Drop in the broken PDF
Drag in the file that refuses to open, even if it has an interrupted-download extension like .crdownload or .part.
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Let the tool rebuild it
The file is first rewritten by the QPDF engine; if that isn't enough, every object is reread one by one and the page tree is rebuilt.
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Check and download
A report shows what was fixed and how many pages were recovered; thumbnails let you check the result before downloading.
Recover as much as possible from a broken PDF
Three methods in a row
Rewriting with QPDF, rebuilding object by object, then rendering the readable pages as a last resort: the tool automatically keeps the best result.
A report you can understand
Damaged header, invalid object table, incomplete file, lost pages: every problem is explained in plain English, without needless jargon.
Text preserved
When the structure is rebuilt, text and images stay intact. Even as a last resort, an invisible text layer keeps search and copy-paste working.
Nothing is uploaded
The file is repaired in your browser: your documents, sometimes confidential, never leave your device.
Why does a PDF become unreadable?
A PDF isn't a simple stream of text: it's a set of objects (pages, fonts, images) linked by an index, the xref table, placed at the end of the file and followed by the %%EOF marker. If a download is interrupted, a USB drive is pulled out during a copy or an email attachment is decoded incorrectly, it's precisely that end of the file that goes missing: the reader can no longer find the index and shows “file is damaged” or “unsupported file type”. A few changed bytes in the middle, a header wiped by badly written software or offsets in the table can also block opening, even though most of the content is often still there.
How the repair works
The tool starts by examining the raw structure: whether the %PDF header and end marker are present, and whether the xref table and each of its entries are valid. The file is then rewritten by QPDF, a reference library for working with PDFs, compiled here to run in the browser. If the file is too damaged, every object is reread from start to finish without relying on the index, the incomplete object at the end is discarded, and the page tree and catalog are rebuilt. As a last resort, the pages the PDF reader can still display are turned into images, with their text as an invisible layer. The most complete result is kept and verified.
What can be recovered, and what can't
A repair can't invent data that isn't there. If a download stopped two thirds of the way through, the pages stored in the last third are lost; the report then tells you how many pages were recovered out of the total the document declares. Likewise, a page whose content was overwritten stays blank. To get a complete document back, the safest option is to download it again or ask for the original. If the PDF is protected by an open password, use “Unlock PDF” first. Finally, a file that isn't a PDF at all, such as a web page mistakenly saved with a .pdf extension, is reported as such.
Frequently Asked Questions
My PDF says “file is damaged”: can it be repaired?
Often, yes. Drop it into the tool: the object table is rebuilt and the pages still in the file are recovered. The report tells you exactly what was fixed and whether any pages are missing.
How do I repair a PDF whose download was interrupted?
Drop the file in as is, even if it ends in .crdownload or .part. The pages already downloaded are recovered; those in the missing part can't be. To get the complete document, start the download again.
Why are some pages missing after the repair?
Because their data is no longer in the file, usually due to an incomplete copy or download. The tool recovers everything it can and tells you how many pages were lost or left blank.
Can the tool open a password-protected PDF?
No, an encrypted PDF whose password you don't know can't be read. If you know it, first remove the protection with “Unlock PDF”, then repair the file if needed.
Are my documents uploaded to a server?
No. The whole repair happens in your browser, on your device: the file is never uploaded, which matters for contracts, statements or medical records.