What this tool does
- Rebuilds the structure — regenerates the cross-reference table and page tree that readers rely on
- Recovers page by page — a page that cannot be read is skipped rather than failing the whole file
- Two passes — a lossless structural rebuild first; if that fails, a rasterising salvage pass that at least recovers how the pages looked
- Honest report — tells you which pages came back and which were lost
What “corrupt” usually means
Most unopenable PDFs are not badly damaged — their index is. A PDF ends with a cross-reference table listing the byte offset of every object. An interrupted download, a crashed export or a file edited by a careless tool can leave those offsets pointing at the wrong place, and a strict reader then refuses the whole document even though the page content is sitting there intact.
The first pass here parses the file leniently, finds the objects wherever they actually are, and writes out a fresh document with a correct index. That recovers the original text and vector graphics exactly. If the damage is deeper, the second pass renders whatever pdf.js can still display and rebuilds the document from those images — you lose selectable text, but you keep the pages.
What cannot be recovered
- Bytes that are genuinely missing — a truncated download has no content to recover past the cut
- Pages whose content streams are corrupt rather than just mis-indexed
- Encrypted files whose password you do not have — unlock those first
Frequently asked questions
Are my PDFs uploaded anywhere?
No — the file is opened and rewritten entirely inside your browser using JavaScript. Nothing is uploaded to a server, so your document never leaves your device.
Will it recover every page?
Not always. It recovers every page it can parse and reports the rest. A file that was truncated mid-download is missing data that no repair tool can invent.
Does repairing reduce quality?
The structural pass is lossless. The fallback salvage pass rasterises pages, so text stops being selectable — the tool tells you which pass it used.
My PDF opens but a page renders blank — will this help?
Often yes. Run it through; a rebuilt page tree frequently fixes pages that a reader skipped over.
What if repair fails completely?
Then the file is damaged beyond what the browser can parse. Try re-downloading or re-exporting the original, which is almost always the real fix.