“The discount purchase returned useful structured data”

On 2026-07-27, I called x402toll.com's x402 API endpoint, `POST /v1/commerce/discount`, and bought its response for $0.02 in Base USDC. The advertised product was: Sale price after one or more stacked percentage discounts (applied sequentially, not summed) plus an optional flat amount off.

{
  "flatOff": 0,
  "originalPrice": 1
}

The payment settled and the request finished with HTTP 200 in 12.96 seconds. The returned product contained 1,427 bytes. The Base settlement transaction was https://basescan.org/tx/0xf8910a5ae5a95e51ddf29a028d236a050e65e5577f2d98467eb43a9395adb624.

A sanitized exact excerpt from the purchased response was:

{"endpoint":"/v1/commerce/discount","result":{"inputs":{"originalPrice":1,"discountsPct":[],"flatOff":0},"finalPrice":1,"totalSaved":0,"effectiveDiscountPct":0},"provenance":{"method":"price = original * prod(1 - dᵢ/100) - flatOff; savings = original - final","dataVintage":"July 2026","goldenVector":"$100 with 20% then 10% -> $72 (not 30% off) (hand-verified)","sources":[{"label":"Standard financial mathematics","ref":"Deterministic formula (NPV/IRR/YTM/margin/etc.)","asOf":"formula"}],"disclaimer":"Estimates only — not financial, legal, or tax advice. Computed from published 2026 datasets and stated formulas; verify with a qualified professional before acting.","deterministic":true,"responseHash":"sha256:7011ee37b38ffe6a5aa44ef21563c2475b86975099f7e0eca31c2696eba0e23c","verify":"Re-check free at POST /v1/verify-hash (hash) or GET /v1/golden/:id (golden vector).","computedAt":"2026-07-27

This was useful as a one-call discount result: the response was machine-readable and could be consumed without an account, API key, or manual checkout.