See the price you were never meant to compare.
Paste a URL. Twenty-four synthetic buyers check it from every angle — geography, device, cookies, referrer, language — and return evidence, with statistics and receipts.
Public-web only · Sample audit completes in ~60 seconds
Same URL.
Different buyer.
Different price.
Location, device, language, cookies, referrer, and session quietly change what a server decides to charge. It is real, widespread, and — done by hand — almost impossible to prove.
rural Iowa · VPN
Manhattan · direct
same seat · same flight · same date — measured, not inferred
Vary one vector. Hold the rest constant.
Jacobi changes a single buyer-context dimension at a time against a fixed baseline, so any price movement can be attributed — not guessed. The Jacobian isolates the driver.
Six vectors — geography, device, browser language, cookies, referrer, and session — are tested in controlled waves. Only differences that clear a Welch t-test are reported as evidence.
Receipts a regulator can read.
Every probe stores the on-page price, native currency, request context, and timestamp — hash-sealed into one reproducible audit trail.
| # | Location | IP type | Agent | Native | USD | Verdict |
|---|---|---|---|---|---|---|
| 01 | US · Manhattan | RESIDENTIAL | iOS · Safari | USD 642.00 | $642 | DEVIANT |
| 02 | AE · Dubai | MOBILE | iOS · Safari | AED 2,356.0 | $641 | DEVIANT |
| 03 | JP · Tokyo | RESIDENTIAL | macOS · Safari | JPY 91,200 | $612 | NORMAL |
| 04 | GB · London | RESIDENTIAL | Win · Edge | GBP 472.00 | $596 | NORMAL |
| 05 | IN · Bangalore | DATACENTER | Win · Firefox | INR 42,600 | $512 | NORMAL |
| 06 | US · Rural Iowa | DATACENTER | Android · Chrome | USD 498.00 | $498 | CLEAN |
The whole audit, in one readout.
Baseline, highest observed, the delta, statistical confidence, and the dominant driver — resolved into a single readout you can hand off or export as an audit-ready report.
Built to be defended.
Native-currency capture
Prices recorded in the real on-page currency first, with a USD-normalized comparison alongside.
Timestamped evidence
Each observation is time-stamped and ordered, so any result can be reproduced and defended later.
Real vs inferred, separated
Directly observed agents are never mixed with inferred ones. Inferred values never appear as raw evidence.
Controlled probe accounting
Agent counts, network tiers, and blocked requests are reported in full — no silent gaps in the sample.
Public-web only
Jacobi reads exactly what any buyer could see. No logins, no private data, nothing behind a wall.
Audit-ready export
Summary, figures, and a complete evidence appendix, sealed into a research-grade PDF.
Stop guessing. Start auditing.
24 synthetic buyers · 6 context vectors · one URL