Fix a PDF that suddenly won't open
A PDF that was fine yesterday and refuses to open today is almost always suffering from the same problem: its internal index — the cross-reference table every PDF viewer uses to locate page content — got corrupted or truncated, usually from an interrupted download, a buggy export, or a crashed editing session. The actual content is often still there. DocZap's Repair tool re-parses the file as leniently as possible and rebuilds that index from scratch.
What this can and can't fix
This works well for the most common failure: a broken or missing cross-reference table, a bad startxref offset, or a cut-off trailer section. It can't recover a file where the actual page content itself has been overwritten or deleted — if there's nothing readable left to rebuild, DocZap will tell you rather than hand back an empty file.
Repaired without ever leaving your device
The repair runs entirely in your browser using pdf-lib. There's no upload step where your (possibly sensitive) file sits on someone else's server while a repair service works on it — the recovery happens locally, and the fixed file never leaves your device.