Validate a PDF and find out what is wrong with it
The PDF Validator opens a PDF the way a careful engineer would and checks its internals: the header and version, the end-of-file marker, the cross-reference table that tells readers where every object lives, the trailer, broken references, fonts, images, page boxes, encryption, scripts and attachments. You get a clear green, amber or red verdict and a plain-English explanation for every finding.
Use it when a PDF will not open on one device but does on another, when a printer or upload portal rejects a file, when a form looks wrong, before archiving important records, or simply to see whether an attachment from a stranger contains JavaScript, launch actions or embedded files.
The PDF is analysed entirely in your browser with pdf-lib, pdf.js and a purpose-built structure checker. Nothing is uploaded, which makes it safe for confidential and legal documents.
How to check a PDF for errors
- Drop a PDF onto the upload area or click to choose it. The check starts immediately.
- Read the verdict at the top: green for no problems, amber for warnings, red for damage or risky content.
- Open each section — Structure, Security, Fonts, Images, Pages, Standards and Document — to see every check with its explanation. Sections with findings open automatically.
- Review the font table (embedded or not) and the image table (size, colour space, compression and pages).
- Press “Download report (.txt)” or “Copy report” to share the results with a colleague, printer or IT team.
PDF Validator features
Independent cross-reference check
Every offset in the classic xref table or cross-reference stream is compared with the actual object position, and shifted offsets are measured and explained.
Two parsers, warnings captured
pdf-lib reads every object and pdf.js parses every page’s content and fonts; their warnings about damaged objects, fonts and repairs are shown in the report.
Security review
JavaScript, launch actions, embedded files, form submission targets, external links, XFA forms and encryption permissions are all listed.
Font and image inventory
See which fonts are embedded or subset, and each image’s pixel size, colour space and compression.
Page box sanity
MediaBox, CropBox, BleedBox, TrimBox, ArtBox and rotation are checked on every page.
Standards detection
PDF/A, PDF/X and PDF/UA claims are detected from XMP metadata and output intents, with obvious contradictions flagged.
What the checks mean
| Check | What it looks at | Why it matters |
|---|---|---|
| Header and version | “%PDF-1.7” at the very start | Missing or misplaced headers mean the file is not a PDF or was wrapped by other software |
| %%EOF and startxref | The end-of-file marker and the pointer to the cross-reference data | A missing marker almost always means an interrupted download or upload |
| Cross-reference table | Byte offsets of every object | Wrong offsets force readers to rebuild the index; some fail or lose pages |
| Trailer | /Root, /Info, /ID and /Encrypt entries | Without /Root nothing can be displayed; /ID is required for encryption and PDF/A |
| Broken references | Links between objects that lead nowhere | A missing font, image or page resource shows up as blank or wrong content |
| Fonts | Embedded font programs | Non-embedded fonts are substituted, changing how text looks and where lines break |
| Page boxes | Media, crop, bleed, trim and art boxes | Inconsistent boxes cause unexpected cropping and print rejections |
Green, amber and red
Green means the structure is internally consistent, every page parses, and nothing risky was found. Amber means the file works but has something worth fixing — fonts that are not embedded, JavaScript, attachments, outdated Fast Web View data or odd page boxes. Red means real damage (a truncated file, a broken cross-reference table, pages that cannot be parsed) or a dangerous feature such as a launch action.
Damaged files often still open, because readers quietly repair them. The validator tells you when that repair is happening, so you can replace the file with a clean copy before it fails somewhere less forgiving.
PDF/A, PDF/X and PDF/UA: detected, not validated
Archival (PDF/A), print (PDF/X) and accessibility (PDF/UA) standards each contain hundreds of detailed rules. This tool reads what the file claims in its XMP metadata, document information and output intents, and flags obvious contradictions such as encryption or missing fonts in a file that claims PDF/A. It does not certify conformance. veraPDF is the reference open-source validator for PDF/A.
For print jobs, check trim and bleed with the PDF Bleed Checker. To see what changed between two versions of a document, use Compare PDF. Clean up a revealing producer name or title with the PDF Metadata Editor, and shrink heavy scans with Compress PDF.
PDF Validator FAQ
How do I check if a PDF is corrupted?
Drop it into the PDF Validator. A missing %%EOF marker, wrong cross-reference offsets, broken references or pages that cannot be parsed all show up as red problems with an explanation of what went wrong.
How can I tell if the fonts in my PDF are embedded?
Open the Fonts section of the report. The table lists every font, its type, whether it is embedded or subset, and the pages that use it. Fonts that are not embedded are flagged in amber.
Can this PDF validator check PDF/A compliance?
It detects PDF/A, PDF/X and PDF/UA claims and points out obvious contradictions, but it does not perform full conformance validation. Use veraPDF, the reference PDF/A validator, for certification.
Is it safe to check a suspicious PDF here?
Yes. The file is parsed, never executed: scripts are not run and attachments are not opened, and nothing is uploaded. The report tells you whether the PDF contains JavaScript, launch actions or embedded files.
Why does my PDF open fine but get a red verdict?
Most readers silently repair damaged cross-reference tables and missing end markers. The file works there, but stricter software — print workflows, archiving systems, older readers — may reject it. Re-export or re-save the PDF from the original application.
Does the validator work with password-protected PDFs?
Files with only editing restrictions are fully checked, and the permissions are listed. Files that need a password to open can only be checked at the structural level.
Is the validator free?
Yes, with no sign-up or file limits beyond what your device’s memory can handle.