A salary slip can be edited and re-saved and still look real to the eye
Background-check teams, NBFC underwriters, and embassy visa reviewers all face the same pattern: a candidate downloads a real salary slip, opens it in any PDF editor, edits the gross or the net, exports back to PDF. The page renders identically. The file structure does not — and we detect the edit regardless of which tool was used.
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 fraud problem is a digitally altered or fabricated salary slip, we’re the most specific tool for it.
When htpbe? returns INCONCLUSIVE on a salary slip, that’s itself a fraud signal in this context — real salary slips always come from a payroll system, never from a desktop tool.
One REST call, one deterministic verdict
Upload the PDF. The API returns INTACT, MODIFIED, or INCONCLUSIVE with named markers — in about three seconds.
How fake and tampered salary slips actually look
Three real fraud mechanics we catch at the structural PDF layer.
Edit-and-re-save with adjusted figures
Candidate downloads the real PDF from their HRMS, opens it in any PDF editor or spreadsheet, changes the gross or basic, exports as PDF. The producer field reveals an editor — not the payroll system that issued the original. A clean structural fingerprint of tampering, regardless of which tool was used.
Generator-tool fabrication
Online "salary slip generator" sites produce a plausible-looking PDF for any employer name and salary the user types in. These tools leave a recognisable producer signature (often Chrome Headless or a specific PDF library) and miss the institutional metadata authentic payroll exports carry.
Gross-to-net arithmetic that does not reconcile
When a candidate edits the gross figure but forgets the deductions, the math no longer adds up. Row-by-row arithmetic checks across the slip flag this even before structural analysis kicks in — a high-confidence signal that the PDF was hand-edited.
The scale
Why your existing checks miss this
Database lookups verify the person. They do not verify the file.
Both layers matter. Most teams only run one.
Background-verification platforms confirm employment by calling the previous employer or checking a registry. They cannot tell you whether the PDF the candidate uploaded was edited after issuance. KYC and identity vendors verify the identity behind the document — not the bytes inside the PDF. Manual HR review catches obvious fakes (typos, wrong tax codes), but a clean re-save through any editor passes a visual check every time. htpbe? fills the structural-PDF layer those workflows do not provide — and works standalone, without a reference original.
Five forensic layers, one deterministic verdict
Every PDF we receive passes through the same structural pipeline — no model training, no thresholds to tune.
Metadata analysis
Creation and modification timestamps, producer and creator fields, XMP metadata — the first layer exposes basic tampering.
File structure
Xref tables, trailer chain, incremental updates. Any edit after export leaves a structural fingerprint here.
Digital signatures
Signature chain integrity and post-signature modifications produce deterministic markers. Certainty-level signal.
Content integrity
Fonts, objects, embedded content, page assembly. Multi-session edits and inserted objects are visible at this layer.
Verdict with markers
Deterministic output: INTACT / MODIFIED / INCONCLUSIVE, with named markers for every finding — suitable for audit trail.
Salary slip and adjacent payroll PDFs we check
Every type listed below is analyzed at the structural file layer — not the rendered image.
Detection capabilities
Deterministic structural signals. No probabilistic scores, no model training.
Producer signature on the PDF
Real salary slips come from a known HRMS (Workday, ADP, Gusto, Zoho People, GreytHR, RazorpayX) or a payroll engine. When the producer field shows Microsoft Excel, LibreOffice, Chrome Headless, or a generic PDF library, the document was authored on a desktop — not exported from a payroll system.
Incremental update trail
Every save after the original export creates an incremental update section in the PDF — visible in the xref table and trailer chain. Authentic payroll exports have one xref. Edited slips have two or more.
Gross-to-net arithmetic
Table arithmetic across earnings, deductions, and net pay is verified row by row. A single edited number breaks the chain — a marker most generator tools fail to fake.
Font subset divergence across pages
When a slip is edited in multiple sessions or assembled from multiple sources, font subset prefixes diverge between pages. Invisible to the eye, obvious to structural analysis.
Text layer vs. raster layer mismatch
Some fraudsters replace text in the rendered image while leaving the underlying text layer untouched. The two layers stop agreeing — an immediate flag.
Modification timestamp gap
Authentic salary slips have ModDate equal or near CreationDate. A gap of hours, days, or weeks between creation and modification on a "monthly slip" is structural evidence of post-export editing.
Two HTTP calls to verify any salary slip
Buyers can skip this section — developers, the integration is two HTTP calls.
Step 1 — submit the PDF
curl -X POST https://api.htpbe.tech/v1/analyze \
-H "Authorization: Bearer $HTPBE_API_KEY" \
-H "Content-Type: application/json" \
-d '{"url": "https://your-storage/candidate-march-salary-slip.pdf"}'Step 2 — read the verdict (GET /v1/result/{id})
{
"id": "a1b2c3d4-5e6f-7a8b-9c0d-e1f2a3b4c5d6",
"status": "modified",
"modification_confidence": "high",
"modification_markers": [
"Spreadsheet producer detected (Microsoft Excel)",
"Multiple cross-reference tables — incremental updates",
"Modification date 6 hours after creation date"
],
"producer": "Microsoft Excel",
"creator": "Microsoft Excel",
"creation_date": 1709280000,
"modification_date": 1709301600,
"has_digital_signature": false,
"xref_count": 3,
"has_incremental_updates": true
}Producer Microsoft Excel on a slip that should have come from a payroll engine is the smoking gun. Combined with xref_count: 3 and a six-hour gap between creation and modification, the verdict is modified at high confidence — a clear flag for HR or underwriting review.
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 verified 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
Frequently asked questions
modified or inconclusive with a producer mismatch flag.Related solutions and guides
Alternative Lending
Salary slip + bank statement forensics for NBFC and alt-lender underwriting pipelines.
HR & Hiring
Pre-employment document fraud detection for talent ops and BGV operators.
PDF Tamper Detection
The technical pillar — how structural PDF analysis catches edits invisible to the eye.
Fake Form 16 Detection
Indian TDS certificate forensics — same payroll cluster as salary slips.
Fake ITR Detection
Income Tax Return forensics — submitted alongside salary slips as income proof.
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