Diagnose and repair PDFs on your computer

Check your PDF locally and repair a copy only when structural problems can be reconstructed. This is not PDF/A certification or a recovery guarantee.

100% private: everything runs on your computer, your files never leave your device.

Upload your PDF
Review the structural diagnosis
Repair and download a copy when possible

What PDF Doctor does

PDF Doctor examines the internal structure of a PDF that will not open, opens with errors or behaves strangely, tells you whether the damage can be repaired, and if so rebuilds a clean copy and verifies it before letting you download it. The analysis and the repair are performed by a PDF processing engine that runs inside your browser, so the broken file is never uploaded.

The kind of damage it handles is structural: a truncated download, a cross-reference table that points to the wrong offsets, a trailer that was cut off by a failing disk or a mail gateway, objects written by a buggy generator. Those are the files that make readers say the file is damaged or show only a blank page. PDF Doctor does not recover pages that are simply missing from the file, and it is not a PDF/A validation service.

How to diagnose and repair a PDF

Add the PDF. The diagnosis screen opens even when the document is too damaged to preview, which is precisely the point.
Press Analyze PDF. The engine runs a full structural check and, when it finds problems, immediately tests whether a rebuilt copy would pass the same check.
Read the verdict: PDF is structurally valid, Repairable problems found, or Automatic repair was not possible. Open Technical details to see the PDF version, whether the file is encrypted or optimized for web, and the issues found.
If repair is offered, press Repair and download copy. The copy is checked again before the download starts; if it fails that second check you are told so instead of receiving a doubtful file.
Several PDFs at once, with the 7-Day Pass or Pro: press Diagnose and repair N PDFs. Healthy files are returned unchanged and only damaged ones are rewritten, with a summary of how many were valid, repaired or failed.

What it can fix and what it cannot

The repair rewrites the file from scratch: objects are re-read, offsets recomputed, the cross-reference table and trailer regenerated and streams normalised. A common case, a wrong startxref pointer at the end of the file, is corrected with a targeted pre-pass before the full rewrite.

Fixes broken cross-reference tables, wrong object offsets, damaged trailers and stream encoding errors, the usual results of truncation or sloppy generators.
Does not restore content that is not in the file. If pages were never written, no tool can bring them back.
Does not repair corrupt fonts or images inside otherwise valid objects.
Repairing rewrites the PDF, so any existing digital signature becomes invalid. The tool warns you before you proceed.
Password-protected PDFs are refused up front. Remove the password with Unlock PDF if you know it.
A valid file gets no download from this tool: there is nothing to repair, and the diagnosis is the result.

Privacy: the damaged file stays on your computer

The structural engine is compiled to WebAssembly and shipped with OléPDF; it runs in a worker inside your browser tab and reads the file from memory. Nothing is uploaded, no diagnostic data about your document is sent anywhere and no third-party script is loaded. The only download is OléPDF's own code from its own domain. The original file on your disk is never modified: you always get a separate repaired copy.

This is what makes it safe for the documents that most often get corrupted in transit: signed contracts, bank statements, scanned identity documents.

Typical uses

A PDF downloaded from a portal that stopped halfway and now opens as a blank page or triggers an error in the reader.
A report produced by an internal system whose PDF output is rejected by a client's document management platform.
A folder of old files recovered from a backup that need checking, and repairing where possible, before archiving.

Frequently asked questions

Is PDF Doctor free?

Yes. Diagnosing and repairing one PDF at a time is free and unlimited, with no account. Diagnosing several PDFs in one batch requires the 7-Day Pass or Pro.

Is my broken PDF uploaded for analysis?

No. The analysis and the repair run inside your browser with an engine bundled in the app. The file never leaves your computer.

Why does it say the repair was not possible?

Because the rebuilt copy did not pass the structural check, which usually means essential objects are missing from the file. Ask the sender for a fresh copy or re-export the document from its source.

Will a repaired PDF keep its digital signature?

No. Repairing rewrites the file, and any signature that covered the original bytes becomes invalid. If the signature matters, obtain a new signed copy instead.

Is this a PDF/A validator?

No. It checks structural validity, not conformance to the PDF/A archival standard. Use the PDF to PDF/A tool for archival conversion.

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