touchstone

Live 402 challenge

Captured by the enrichment pass, not read just now. Prices can change — always read the 402 the endpoint answers with.

{
  "docs": "https://touchstone.locomot.io/llms.txt",
  "error": "Payment required",
  "accepts": [
    {
      "asset": "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913",
      "extra": {
        "name": "USD Coin",
        "version": "2"
      },
      "payTo": "0xa3091005a76b1480F1897a9D0C2e1c55B7767674",
      "amount": "1000",
      "scheme": "exact",
      "network": "eip155:8453",
      "maxTimeoutSeconds": 300
    }
  ],
  "resource": "https://touchstone.locomot.io/unit",
  "price_usd": 0.001,
  "parameters": {
    "note": "send these as query parameters on the SAME url; a paid request missing any of them answers 422 and takes no money",
    "optional": [
      {
        "name": "notarize",
        "about": "also drand-timestamp the answer"
      }
    ],
    "required": [
      {
        "name": "value",
        "about": "the quantity to convert"
      },
      {
        "name": "from",
        "about": "source unit (name or alias, e.g. mile, kg, °C)"
      },
      {
        "name": "to",
        "about": "target unit, same dimension"
      }
    ]
  },
  "description": "Deterministic unit conversion reproducing NIST SP 811 exact factors (length, mass, volume, energy, power, pressure, force, area, speed, data, angle, frequency + affine temperature). Every answer signed. Free sample, no payment required: GET /play/unit",
  "free_sample": "https://touchstone.locomot.io/play/unit",
  "x402Version": 2,
  "sample_response": {
    "url": "https://touchstone.locomot.io/unit/example",
    "note": "free, and it IGNORES your parameters -- a fixed input, so you can see the exact response shape before paying"
  },
  "pay_once_instead": {
    "buy": "POST https://touchstone.locomot.io/credits   (x402, $1.00 buys $1.20 of credit)",
    "why": "one payment, then no wallet and no signature per call",
    "then": "call this same URL with header  Authorization: Bearer tsk_...",
    "balance": "GET https://touchstone.locomot.io/credits/balance   (free)"
  }
}

Accepts

The payment requirements as published to the catalog. Read the live 402 before paying — a price here is a claim, not a quote.

[
  {
    "asset": "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913",
    "extra": {
      "name": "USD Coin",
      "version": "2"
    },
    "payTo": "0xa3091005a76b1480F1897a9D0C2e1c55B7767674",
    "amount": "1000",
    "scheme": "exact",
    "network": "eip155:8453",
    "mimeType": "application/json",
    "resource": "https://touchstone.locomot.io/unit",
    "maxAmountRequired": "1000",
    "maxTimeoutSeconds": 300
  }
]

Provenance

Seen in the source catalog

—

Last indexed by Roundhouse

2026-09-23 21:45Z

Last enriched (probe, favicon, geo)

2026-09-19 03:15Z

x402 version

1

Max timeout

300s

Liveness probe

HTTP 402