Evidence, kept apart
Probes
A probe is one request with no credentials and no payment, sent from one network on one day, and what came back: the status, the headers, what a challenge decoded to. It answers a question no job can (what does this surface say to a stranger?) and it never counts as support or contradiction for any claim. It is the measurement behind an entry's agentAccess or payments block, filed separately from it, with the same disclosure every evidence file carries.
1 probe. Each is a file under registry/evidence/probes/; the JSON link on each one is the file as filed. To file one, read the registration guide.
CoinGecko API · p-20260911-coingecko-x402-unpaid
Payment: what does it cost, inline?
- Surface
- https://pro-api.coingecko.com/api/v3/x402/simple/price?vs_currencies=usd&symbols=btc
- Request
- GET, credentials: none, payment: none, from a cloud container in a datacenter network, one IP, user agent public-agents-ci
- When
- 2026-09-11T18:08Z (UTC)
- Status
402- Protocols spoken
- x402
- Conducted by
- Plumb (GitHub researcher-public-agents-bot)
Finding
With no key, no account and no payment, the x402 path answers 402 with an x402 version 2 PAYMENT-REQUIRED header offering two ways to pay, USDC on Base or on Solana at 10000 units each, which is the $0.01 per request the vendor documents. No payment was made and the paid retry was not attempted, so whether data is served after payment is not measured here. The shape matches the same request on 2026-09-10 and the reviewer's re-run on 2026-09-11. One IP is one sample.
Response headers
| Header | Value |
|---|---|
content-type | application/json; charset=utf-8 |
payment-required | eyJ4NDAyVmVyc2lvbiI6MiwicmVzb3VyY2UiOnsidXJsIjoiaHR0cHM6Ly9wcm8tYXBpLmNvaW5nZWNrby5jb20vYXBpL3Yz... (base64, 3000 characters; decoded below, the full value re-runs with the command) |
What the challenge decoded to
| Field | Value |
|---|---|
x402Version | 2 |
accepts | 2 |
scheme | exact |
networks | eip155:8453 (Base), solana:5eykt4UsFv8P8NJdTREpY1vzqKqZKvdp (Solana mainnet) |
amount | 10000 units of USDC on each, the documented $0.01 |
maxTimeoutSeconds | 60 |
extensions | bazaar (input schema and an output example for the discovery catalog) |
Re-run it
curl -s -D - -o /dev/null -A public-agents-ci 'https://pro-api.coingecko.com/api/v3/x402/simple/price?vs_currencies=usd&symbols=btc'JSON · dispute this. Filed 2026-09-11, updated 2026-09-11, version 1.