PDF Tamper Detection — Find Out If Your Document Was Altered
HTPBE.tech is a PDF modification detection tool that identifies whether a document was altered after creation — free in the browser, with an API for automated workflows.
Used to detect altered invoices, forged contracts, and tampered certificates.
What PDF Tamper Detection Looks For
Every PDF carries hidden evidence of its history. Here is what to look for.
Timestamp anomalies — the most common tampering signal
A PDF carries internal creation and modification dates. When the modification date follows the creation date by days or months on a document that should never have changed, this is the first and most common sign of tampering.
Known editing tool in the producer field
The PDF records which software last processed it. When the producer field shows a tool designed exclusively for editing existing PDFs — such as iLovePDF, PDF24, or Smallpdf — rather than the original document application, this is a strong indicator the file was modified after creation.
Incremental revision layers
PDF editors often append changes to a file rather than rewriting it. This leaves multiple revision layers that are invisible in a PDF viewer but detectable through structural analysis. Each additional layer represents a post-creation edit.
Removed or invalidated digital signature
A digital signature cryptographically locks a document’s contents. If a signed document is later modified, the signature becomes invalid. If the signature was removed entirely after tampering, that absence is itself evidence of forgery.
The Easy Way: Use HTPBE
All checks run automatically in seconds — no technical knowledge required.
Upload your PDF
Drop any PDF up to 10 MB onto the checker. No account required.
Tamper detection runs automatically
All detection layers — metadata, structure, signatures, and content — run simultaneously in under 5 seconds.
Get the modification detection result
A clear verdict — modified, intact, or inconclusive — with a plain-language list of every finding.
Frequently Asked Questions
What is PDF tamper detection?
PDF tamper detection is the process of analysing a PDF document’s internal data to determine whether it was modified after its original creation. It examines metadata timestamps, file structure revision history, digital signature integrity, and application fingerprints to identify signs of tampering.
How do I know if a PDF has been tampered with?
Upload it to HTPBE. The tool analyses the PDF’s internal metadata, file structure, revision history, and digital signatures — all in under 5 seconds. If the file was modified after creation, the analysis returns a “modified” verdict with a plain-language list of specific findings.
Can PDF tamper detection catch all types of tampering?
No automated tool catches everything. HTPBE reliably detects the most common tampering methods — metadata editing, incremental updates, signature removal — but sophisticated forgeries that rewrite the entire file from scratch may not leave detectable traces.
Is PDF tamper detection free?
Yes. The web tool is completely free with no upload limits. No account required. API access for automated tamper detection workflows starts at $15/month.