Invoice Tamper Detection API
Detect tampered or fake invoices before payment. A single API call reveals whether a PDF invoice was modified after generation or fabricated from scratch — catching altered amounts, swapped payee details, changed account numbers, and supplier-impersonation invoices that eyes miss.
HTPBE? analyzes the structural layer of the PDF file — the layer that records every edit, even invisible ones. We don’t inspect holograms, phone photos, or ID biometrics. If your AP fraud problem is a digitally tampered or fabricated invoice PDF, we’re the most specific tool for it.
When HTPBE? returns INCONCLUSIVE on an invoice, that’s itself a fraud signal in this context — real vendor invoices come from accounting software (QuickBooks, Xero, SAP, NetSuite, Zoho), e-invoicing platforms, or ERP systems, never from a desktop tool.
The problem
Why altered invoices pass manual review
A fraudster intercepts a legitimate invoice PDF, opens it in a free online editor, changes the bank account number or payment amount, and sends the modified file. The wire goes out to the attacker. Visually, the invoice looks identical — same logo, same layout, same font.
The modification is invisible to the human eye but not to a forensic analyzer. PDF editors leave structural traces: extra xref tables, incremental update records, and metadata timestamps that do not match. HTPBE? surfaces these traces automatically.
According to the Association of Certified Fraud Examiners, billing fraud accounts for 43% of all occupational fraud cases. A single prevented fraudulent payment typically covers months of API subscription costs.
Typical invoice fraud scenario
- 1Vendor sends a legitimate invoice PDF via email
- 2Attacker intercepts or spoofs the vendor’s email account
- 3PDF opened in iLovePDF, SmallPDF, or Adobe Acrobat
- 4Bank account number or amount edited
- 5Modified file forwarded to AP team
- 6Payment sent to fraudster’s account
What this looks like
Document fraud in 2026 — three concrete patterns
Three real fraud mechanics we catch at the structural PDF layer.
Vendor sends a legitimate invoice PDF via email
Attacker intercepts or spoofs the vendor’s email account
PDF opened in iLovePDF, SmallPDF, or Adobe Acrobat
Bank account number or amount edited
Modified file forwarded to AP team
Payment sent to fraudster’s account
The detection gap
KYC platforms check the document. HTPBE? checks the file.
Two different checks — both matter.
KYC & identity platforms
Plaid · Persona · Alloy · Jumio
- Is this a real bank statement template?
- Does the account number match the identity?
- Is the document format consistent with the issuing bank?
Detects fake documents. Does not detect edited real documents.
HTPBE? tamper detection API
Structural PDF integrity
- Was this specific PDF file modified after it was generated?
- Do metadata timestamps match the file structure?
- Were digital signatures valid at the time of signing?
What HTPBE? checks
What the API detects in invoice PDFs
Five forensic layers analyzed on every request
Multiple xref tables
An unmodified invoice has one xref table. A second table means content was added after the original save — the most common marker of invoice tampering.
Incremental update chain
PDF editors append changes without rewriting the original bytes. HTPBE? counts the update chain length — one update is unusual, two or more is highly suspicious.
Producer/creator mismatch
Genuine invoices are generated by accounting software (QuickBooks, Xero, SAP). If the producer field shows a PDF editor (iLovePDF, SmallPDF, QPDF), the file was processed after generation.
Date inconsistency
CreationDate and ModDate are metadata fields that PDF editors update automatically. A ModDate weeks after CreationDate on an invoice is a direct tampering signal.
Digital signature bypass
If the original invoice was digitally signed and content was added after signing, HTPBE? flags it as modified with “certain” confidence — the highest possible verdict.
Tool fingerprint analysis
Every PDF tool leaves a distinct fingerprint in the file structure. HTPBE? cross-references against a database of 200+ known tools to detect editing software.
Share with engineering
Wire this into your intake pipeline in under a day
Two API calls — one POST to submit the PDF, one GET to retrieve the verdict. Forward this page to your engineering team; the full API reference, quotas, and copy-paste examples in cURL, JavaScript, Python, PHP, Go, and Ruby are one click away.
Pricing
Self-serve plans, no sales call
All plans include the same forensic checks. Pick the quota that matches your monthly document volume.
manualStarter
$15/mo
30 checks/mo
Manual spot-checks and integration testing
most commonGrowth
$149/mo
350 checks/mo
Active document processing pipelines
high volumePro
$499/mo
1,500 checks/mo
High-volume automation and API integrations
Enterprise (unlimited, on-premise available) — see full pricing
API key on signup. Free test environment on every plan. No card required.
Customer Stories
Teams that stopped document fraud
Compliance, finance, and risk teams use HTPBE? to catch manipulated PDFs before they become costly mistakes.
Caught an invoice where the total had been changed by less than a thousand dollars. Without this I would have approved it without a second look.
Sarah M.
AP Manager
United States
We had three applicants in the same week with bank statements that looked completely fine. Two of them were flagged as modified. You simply cannot see this by reading the document — it is in the file structure.
Lars V.
Risk Analyst, Online Lending
Netherlands
Salary slips were coming with altered figures. We identified two problematic files before the placement was finalised.
Priya K.
HR Operations Lead
India
Since we started checking documents this way, we stopped two applications early in the process that would have been very difficult to reverse later.
Julien R.
Fraud Analyst, Fintech
France
Some applicants were sending PDFs that looked authentic but had been edited in ways not visible to the eye. We now ask for checked originals when something is flagged. Already saved us from a few bad decisions.
Marta S.
Compliance Coordinator
Spain
One invoice was caught because there was a mismatch between the document dates and structure. That particular case would have cost us significantly.
Tariq A.
Finance Manager
United Arab Emirates
FAQ
Frequently asked questions
How does the API detect a tampered invoice?
Can it catch invoice fraud if the original was never signed?
What does "inconclusive" mean for an invoice?
inconclusive means the invoice was created with consumer software (Microsoft Word, Google Docs, or a desktop PDF printer) rather than with dedicated invoicing software. The file lacks the institutional metadata needed to detect tampering. This is itself a risk signal — legitimate vendor invoices from established businesses are generated by accounting systems, not Word.How many invoice checks per month does a typical AP team need?
Secure your workflow
Create your account — API key on signup, free test environment on every plan.
From $15/mo. No sales call. Cancel any time.