How do I repair a corrupted PDF that will not open?
Upload the damaged PDF to Sealique: its structure is rebuilt on the server and the readable pages become a clean file in your library, ready for a digital signature.
A download that stopped halfway, an e-mail attachment that was mangled, a scan the scanner saved badly: the viewer says the file is damaged. Most such files still contain their pages; the tool rebuilds the index that points to them and writes a file every viewer can open.
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Key facts
- Repair PDF on Sealique rebuilds a damaged PDF of up to 50 MB and saves the recovered pages as a clean file, included with an account.
- The cross-reference table, the trailer and broken streams are reconstructed on the server; the job page lists the problems that were found.
- When the structure is too damaged for a full rebuild, the pages that can still be read are copied into a new file.
- A password-protected file must be unlocked first; a file with no readable pages is reported as unrecoverable.
- The repaired copy is a normal document in your library and can be edited, compressed or signed.
How is a PDF rebuilt?
A PDF ends with a table that says where every object sits in the file; when that table or the trailer is wrong, viewers give up. On Sealique servers the file is scanned object by object, the table is reconstructed from what is actually there, damaged streams are decoded as far as possible and everything is written to a fresh, compressed file. If even that fails, each page that can still be parsed is copied into a new document.
Repair, then archive or sign
A repaired file is a good candidate for PDF/A if it must be kept for years, and for a PAdES digital signature if its content must be proven unchanged from now on; both tools work on the repaired copy in your library.
Repair PDF, step by step
Open Repair PDF
Sign in, open PDF tools and choose Repair PDF.
Choose the PDF
Drop the damaged file (up to 50 MB). If it asks for a password, run Unlock PDF first.
Repair
Press Repair. The structure is rebuilt on the server; the job page lists what was fixed and how many pages were recovered.
Check the result
Open the repaired copy from your library and check the pages before you rely on it.
Repair PDF is included with a Sealique account; the processing happens in your browser and on our servers, nothing is shared with third parties.
What Repair PDF includes
- Cross-reference table and trailer rebuilt
- Damaged streams recovered
- Readable pages saved when the rest is lost
- Problems found listed on the job page
- Repaired copy in your library
- Works from a phone or a computer
Questions people ask
What kinds of damage can be fixed?
A broken or missing cross-reference table, a damaged trailer or header, truncated or badly compressed streams and inconsistent object numbering: the usual results of an interrupted download or transfer.
A file whose page content was overwritten cannot be restored; the tool then says no pages could be read.
Will all pages come back?
Every page whose content is still present is recovered; the job page shows the count. Pages whose data is missing cannot be invented.
Does repairing change the look of the pages?
No. Recovered content is rewritten as it was; objects are only renumbered and compressed.
Why must I unlock the file first?
An encrypted file cannot be rebuilt without its password; Unlock PDF removes the encryption with the password you have.
Does it cost anything?
No. It is included with a Sealique account: no card, no watermark, no daily limit.