Repair PDF
Four-strategy repair: the result names which strategy worked.
Repair PDF rebuilds a damaged file using four strategies in turn — ending with a cross-reference rebuild from the object bodies still present in the bytes — and keeps the text where it survives. It recovers files other readers refuse and says clearly when a file is beyond recovery.
Repair PDF tries four recovery strategies in order, stopping at the first that works: a clean re-save, a tolerant re-parse, a cross-reference rebuild that recovers the file from the object bodies still present in its bytes, and — only if all three fail — a visual rebuild that renders every page to an image and leaves the text unselectable. The result tells you which strategy succeeded and what was wrong with the file. Some damage cannot be undone: when a page's fonts or content are no longer in the bytes, the tool says so instead of inventing them. Repair PDF is one of UnboundPDF's 53 free browser-based PDF and image tools: it runs on your own device with no upload, no account and no watermark, and reports what it measured on the output.
How to repair PDF — steps & common uses
Updated 18 August 2026
What people use Repair PDF for
People with a PDF that will not open or renders wrong — recovering a file that was truncated, corrupted, or partly downloaded.
- Open a file that will not render
- Recover a truncated download
- Fix a corrupted PDF
- Rescue a partly-saved document
How to repair PDF
- Add the damaged PDF; repair is attempted entirely on your device.
- Click Repair PDF to run the recovery strategies in sequence.
- The tool tries a clean re-save, a tolerant re-parse, a cross-reference rebuild, then a visual rebuild if all three fail.
- Preview the recovered file and download it, noting which method succeeded.
Good to know: Four strategies are tried in order and the result names which one worked — on our eight-file damage corpus seven came back as real PDFs with 98–100% of their text, and the eighth came back with all 51 pages and its missing text named rather than guessed.
Questions about Repair PDF 7
Are my files uploaded to a server?
No. UnboundPDF processes PDFs locally in the browser — documents are not uploaded to a server. We have no backend that receives, stores, or scans your files.
Can it fix any broken PDF?
Not always. This is a repair with four strategies, the result naming which one worked, and badly corrupted files may be unrecoverable. When only the visual rebuild works, the recovered pages become images and text is no longer selectable.
Does it ever replace a font it cannot find?
The tool never substitutes a font it did not find. If a page's fonts are gone, it returns the page and says the text is unreadable rather than drawing different letterforms in its place.
How does it try to repair the file?
It runs four strategies in order: a clean structural re-save, a more tolerant re-parse, a cross-reference table rebuild from the object bodies still present in the file's bytes, and finally rebuilding pages from rendered images as a last resort.
What kinds of damage can it fix?
It rebuilds a PDF's internal structure, which recovers many files with broken cross-references or truncated data. Severely damaged files may only partly recover.
Will I get all my pages back?
Often yes, but recovery depends on how much of the file survived. Anything unreadable cannot be reconstructed.
Does repair change my content?
It aims to preserve everything and only rebuilds the structure. Check the result, since a damaged source may have lost data before you started.
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How your files are handled
The work runs on your own device, inside the browser tab — so there is no server to send your document to.
- Nothing is uploaded. We have no backend that receives or stores documents, so we cannot see your files during processing or after.
- Your device does the work. Large documents are handled in stages, pages are rendered as you reach them, and each job is checked against your device before it starts — so a long run takes longer on a phone than on a laptop, nothing is queued behind other people's jobs, and you can stop a run at any point without touching your original file.
- No account and no watermark. The output is a clean file you can use anywhere, with no sign-up and no hourly cap.
More optimize tools
Other free PDF utilities that work the same way — in your browser, no sign-up.