Repair PDF Online — rebuild a broken PDF's structure, right in your browser
Upload a PDF that won't open properly. This tool reconstructs the document's object graph and writes a fresh, valid structure — fixing broken cross-reference tables, corrupted trailers, or bad startxref pointers.
Verified during development, and re-checked on every repair. Before release, this mechanism was tested by deliberately damaging real PDFs in four distinct ways, and the repaired output was confirmed to open correctly in an independent PDF library (pypdf) each time — a one-time development verification. At runtime, the repaired output is validated by a separate structural validation pass and re-rendered page by page before you're told it succeeded. If a file is too damaged to recover, you're told plainly rather than given a broken result dressed up as a fix.
The repair console
Upload a damaged PDF — repair is attempted automatically.
Nothing is uploaded. The file is read, repaired, and re-downloaded entirely inside this browser tab.
Drop your damaged PDF here
or browse files (recommended max 150 MB)
Structural damage, not missing content
Many PDF opening failures come from damaged structure rather than missing page content. This tool targets those structural failures — it can't recreate bytes that were never saved.
What this tool genuinely fixes
- A broken or missing cross-reference table — the index a PDF uses to locate its own content.
- A corrupted trailer or a trailer pointing to the wrong root object.
- A bad startxref pointer left over from an interrupted save or a bad transfer.
- Garbage bytes appended after the file's real end, common after a corrupted download.
What it can't fix
- A file truncated mid-content — if a page's data was physically cut off, that data is gone.
- A file that isn't actually a PDF — a renamed file of a different type won't become one.
- A password-protected PDF you don't have the password for — that's a different tool's job.
- Metadata lost with a truncated trailer — if the title/author reference was in the cut-off portion, it can't be recovered.
How this was verified before shipping
Before release, the repair pipeline was tested against deliberately damaged PDFs covering four structural failure cases: a scrambled cross-reference table, a missing trailer, a bad startxref pointer, and trailing garbage after the document's real end. Each repaired result was checked by re-opening the output with pypdf under strict parsing to confirm that the rebuilt PDF was readable.
The honest failure case, tested too
A fifth test file was truncated mid-object, genuinely destroying content rather than just the structure around it. The repair pipeline correctly failed to load it rather than producing a hollow or corrupted "success" — confirming the tool reports failure honestly instead of pretending in the one case where nothing can actually be recovered.
One upload, no options to configure
Repair either works or it honestly doesn't — there's nothing to choose beforehand.
Upload the damaged PDF
Drag it onto the upload area, or click Select PDF — even a file that fails to open elsewhere.
Repair runs automatically
The file is re-parsed and rebuilt with a fresh structure. One of three outcomes follows:
Preview the result
Page through the recovered document to confirm the content looks right before downloading.
Download the repaired file
The rebuilt PDF is ready with a fresh, valid structure — no further steps needed.
When a PDF suddenly won't open
Common real-world corruption scenarios, and whether structural repair can help.
| Situation | What's likely wrong | Can this help? |
|---|---|---|
| Broken or incomplete structure | The file's cross-reference data, trailer, or startxref pointer is inconsistent with the objects still present in the file. | Often, yes |
| Interrupted download | If the download cut off actual page content, that missing data cannot be reconstructed. If the content survived and only the PDF structure was damaged, repair may help. | Depends on damage |
| "File is damaged" error | Usually a broken cross-reference table from an interrupted save or an editing tool crash. | Often, yes |
| Copied from unreliable storage | A damaged copy may contain inconsistent cross-reference data or other structural corruption while some of the original objects remain intact. | Worth trying |
| File stops rendering partway | Content genuinely missing from a specific page onward — not a pointer problem. | Usually not |
| "Please enter a password" prompt | Not corruption — the file is intentionally protected. | Use Unlock PDF instead |
| File won't open in anything, anywhere | May not actually be a PDF, or may be extremely severely damaged. | Worth trying, not guaranteed |
How re-parsing actually fixes the file
There's no trick here — rebuilding the structure from scratch is the whole mechanism.
Check the file's own structure directly, first
Before attempting repair, the file's declared cross-reference table (or cross-reference stream) and trailer are decoded and checked for self-consistency — do the offsets it claims actually point to the objects they say they do? This decides whether repair is needed at all, rather than just checking whether a lenient viewer happens to tolerate the file.
Reconstruct the document's object graph
If real damage is detected, the corrupted index is bypassed. The PDF engine re-parses the document's underlying object graph directly from the remaining bytes, discovering object definitions and assembling a clean hierarchy.
Resolve catalog root and document trees
If the trailer or root pointer is corrupted, the parser resolves the genuine document catalog (/Root) from within the object tree, connecting pages, resources, and font references into a coherent whole.
Rebuild a fresh cross-reference table and trailer
With all valid objects and page trees re-indexed, an entirely new, compliant cross-reference table and trailer dictionary are serialized — discarding the damaged structure entirely.
Validate the result before calling it a success
The newly written structure is evaluated by a separate structural validation pass, then opened with the viewer engine and every page is re-rendered. Only if all checks pass is the repair reported as successful — the tool does not blindly assume its own output is valid.
If this fails, nothing is faked
If structural re-parsing fails or its output fails the separate validation pass — because fundamental content is destroyed — the process attempts page-by-page visual recovery. If even that fails, the failure is reported plainly rather than outputting a hollow or misleading file.
When something doesn't work as expected
What's actually happening, and the fastest way through it.
"This file couldn't be repaired"
The damage likely destroyed actual content, not just the structure pointing to it — there's nothing left to rebuild from.
Check if you have an earlier backup or a different copy of the original file.
"This file already opens correctly"
Your PDF didn't have structural damage — whatever issue you saw elsewhere has a different cause.
Check whether the actual problem is a password, an unsupported feature in a specific viewer, or something else entirely.
The repaired file is missing its title or author
That metadata lived in the document's Info dictionary reference, which was likely lost if the file was truncated before its trailer.
Re-add the title and author manually with a metadata editing tool if you need them back.
"Password required" instead of a repair result
The file is intentionally password-protected, which isn't corruption and isn't something this tool addresses.
Use Unlock PDF if you know the password, or contact whoever protected the file.
Some pages are missing after repair
Content for those specific pages may have been in the part of the file that was genuinely destroyed.
Check whether an earlier or different copy of the file has the missing pages intact.
"Couldn't be repaired"
Why: Actual content destroyed, not just structure.
Fix: Check for a backup copy.
"Already opens correctly"
Why: No structural damage found.
Fix: Look for a different cause.
Missing title or author
Why: Info dict reference was in the truncated part.
Fix: Re-add metadata manually.
Password required
Why: Intentional protection, not damage.
Fix: Use Unlock PDF instead.
Some pages missing
Why: That content was genuinely destroyed.
Fix: Look for another copy.
Getting the best chance at a full recovery
A few habits that improve the odds before and after repair.
Try the original download or copy first
If you have another copy of the file — a different download, an email attachment, cloud storage — try that before assuming repair is needed.
Keep the damaged original
Don't delete the corrupted file until you've confirmed the repaired version has everything you need.
Page through the entire result
Structural repair can succeed while still missing a page or two if that specific content was destroyed — check the whole document, not just the first page.
Check metadata separately if it matters
If the title, author, or other document properties are important to you, verify they survived — they're the most likely casualty of a truncated trailer.
Re-save from the source application if possible
If you still have access to whatever created the PDF, generating a fresh export is often more reliable than repairing a damaged copy.
Don't re-download over a partially damaged file
If a transfer was interrupted, restarting the download fresh usually gives a better result than trying to repair a half-received file.
Repair PDF FAQs
Start here if you're deciding whether this can help your specific file.
What does this tool actually fix?
It fixes structural damage: a broken or missing cross-reference table, a corrupted trailer, a bad startxref pointer, or extra non-whitespace garbage bytes appended after %%EOF. These are common reasons a PDF suddenly won't open, and they're resolved by re-parsing the document's object graph and writing a fresh, valid structure.
What can't it fix?
If actual content is missing — a file truncated mid-page, a download that was cut off partway through — that data is physically gone, and no tool can reconstruct bytes that were never saved. This tool detects that case and informs you plainly rather than producing a file that looks fixed but is missing content.
Is this just re-saving the file and calling it repaired?
No. Rebuilding the document's object tree and regenerating a compliant cross-reference table and trailer is the genuine repair mechanism. During development, this was verified by deliberately corrupting real PDFs in several distinct ways and confirming an independent PDF library (pypdf) could parse the repaired output where it had rejected the original. At runtime, every repair is validated by a separate structural validation pass and re-rendered page by page before being reported as successful.
Why does the repaired file sometimes lose its title or author info?
If a file was truncated before its trailer, the reference to the document's Info dictionary (which holds title, author, and similar metadata) is lost along with it. The page content can still often be recovered, but that specific piece of metadata cannot be reconstructed if it was never present in what remains of the file.
Is it safe to upload my documents here?
Yes. The entire repair process happens locally in your browser — your files are never uploaded to a server. The page does load its PDF-reading libraries from third-party CDNs, which is a normal dependency for a browser tool like this, but your file never leaves your device.
What happens if I upload an empty file, or something that isn't a PDF?
You'll get an immediate diagnostic message: an empty file is flagged right away, and a file without a valid %PDF- header is flagged as not being a genuine PDF — verified by inspecting the file's actual initial bytes rather than its file extension.