Repair PDF
Attempt to fix broken or corrupted PDF files - 100% client-side
Fix corrupted, damaged, or malformed PDF files that won't open correctly in standard viewers. Our repair tool reconstructs the PDF structure in your browser to recover as much content as possible.
Diagnosing and Recovering Corrupted PDF File Structure
PDF corruption typically occurs in one of several ways: interrupted downloads that produce truncated files missing the trailer and cross-reference table; failed disk writes that corrupt specific byte ranges mid-file; PDF generators with bugs that produce technically invalid objects or malformed streams; or version-specific compatibility issues where a PDF contains constructs that certain viewers reject.
A PDF's structure depends on its cross-reference table (xref) or cross-reference stream — an index that maps object numbers to their byte offsets in the file. If this index is corrupt or missing (as with truncated downloads), viewers can't locate objects and refuse to open the file. A repair operation performs a linearization scan, reading the file sequentially to locate all PDF objects by scanning for their headers (object number, generation number, 'obj' keyword), then reconstructs the xref from scratch.
Font stream corruption, truncated image data, and broken stream lengths are also common issues. Repair attempts to reconstruct these objects by extending the parsing tolerances beyond what strict PDF viewers enforce, accepting partially valid stream data rather than failing on the first parse error encountered.
Fix truncated PDF downloads
Recover PDFs that were partially downloaded and are missing the trailer or xref section.
Repair files corrupted by disk errors
Attempt recovery of PDFs damaged by storage drive failures, bad sectors, or file system errors.
Fix malformed PDFs from buggy generators
Repair technically invalid PDFs produced by software with PDF generation bugs that stricter viewers refuse to open.
- 1
Upload the corrupted PDF
Select the PDF file that is failing to open or displaying errors. The tool will attempt to parse it regardless of the reported error.
- 2
Run structural repair
Click Repair PDF to begin the recovery process — the tool scans for all recoverable objects, reconstructs the xref table, and rebuilds trailer structures.
- 3
Download repaired output
Download the repaired PDF and verify it opens in your preferred viewer. Severely corrupted files may have some pages or content unrecoverable depending on which byte ranges are damaged.
xref reconstruction from object scanning
Rebuilds the cross-reference table by scanning for object headers in the raw file data, recovering files with missing or corrupted xref sections.
Truncation recovery
Recovers maximum content from truncated files that are missing data at the end, common in incomplete downloads.
Tolerant stream parsing
Accepts partially corrupt FlateDecode streams and invalid stream length values, extracting what can be decoded rather than aborting on first error.
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