Not every PDF is what it claims to be. Verify before you trust.
PDFs are the default document format for business — contracts, certificates, financial records, and identity documents all travel as PDF files. But PDFs are also easy to edit, and the edits are invisible to anyone who doesn't look at the file forensically. TamperCheck does that forensic look for you.
The problem
The PDF trust problem
PDF was designed to be a portable, fixed-layout format — but it was never designed to be tamper-proof. Anyone with Adobe Acrobat, LibreOffice, or a free online PDF editor can change text, replace images, and alter metadata without leaving visible traces to the naked eye.
Digital signatures help when they're present, but the majority of PDFs in business workflows — bank statements, payslips, invoices, certificates — are not digitally signed. The recipient has no way to verify authenticity without forensic analysis.
The rise of generative AI has made the problem worse. Tools can now produce entire PDFs from text prompts — complete with institutional branding, correct formatting, and plausible content. These documents have never existed in paper form and have no chain of custody to verify.
What we detect
Forensic signals that expose fraud
Text layer integrity
TamperCheck compares the PDF text layer (what copy-paste sees) against the rendered pixel layer (what you see on screen). Edits that modify text objects without re-rendering the page leave detectable mismatches.
Font catalogue consistency
Every PDF embeds or references specific fonts. When a field is edited with a different tool, the font catalogue changes. TamperCheck detects mixed font sources, missing glyphs, and metric inconsistencies.
Object stream analysis
PDFs are structured as object streams. Edits that add, remove, or modify objects leave structural fingerprints — orphaned references, incremental save markers, and inconsistent cross-reference tables.
Compression artifact analysis
Different tools compress images and content differently. A scanned document re-saved through an editor shows compression boundary artifacts that TamperCheck's CV layer detects.
Metadata and producer fingerprint
The PDF's metadata (creator, producer, creation/modification dates, tool version) tells a story. Genuine documents from institutions have consistent metadata; edited files show traces of editing tools.
AI-generated content detection
Fully synthetic PDFs exhibit characteristic noise patterns, rendering quirks, and structural signatures that distinguish them from documents produced by real institutions or scanners.
The solution
How TamperCheck verifies PDF authenticity
Upload any PDF — bank statement, certificate, contract, invoice — and TamperCheck returns a forensic verdict in seconds. No forensics expertise required.
How it works
- Works on any PDF — financial, legal, identity, academic, or commercial documents
- Three analysis layers — structural forensics, computer vision, and AI adjudication
- Pinpointed findings — each issue is tied to a specific region or element of the document
- Handles scans too — phone photos and flatbed scans of paper documents are first-class inputs
- Single API endpoint — upload, get verdict JSON, done
- $0.50 per document with $5 in free credits to start
FAQ
Common questions
See it working on your documents
Start with $5 in free credits — no contract, no card required. Upload your first document and get a verdict in seconds.