API-existence Oracle: symbol /v1/symbol/exists APIPOST /v1/symbol/exists · x402 API by API-existence Oracle: symbol

Deterministic symbol existence for PyPI and npm packages: functions, classes, methods, constants with signatures and deprecation flags, extracted from real artifacts. Negative answers include closest matches and signed proof. $0.005 USDC per check.

https://attester.dev/v1/symbol/exists

What does this x402 API do?

API-existence Oracle: symbol /v1/symbol/exists API. This is an x402-gated POST API resource from API-existence Oracle: symbol. TOLL·402 did not invoke this route automatically because doing so was not considered safe. No normalized USD price is recorded; the listing names Base. No settled paid call has been verified.

Published price: No normalized USD price is recorded
Networks: Base
Latest evidence: TOLL·402 did not invoke this route automatically because doing so was not considered safe
Resource ID: 081fe34bcaf4d86f1ab90a73

USE THIS RESOURCE

Start with a quote-only recipe. Payment signing stays in your project.

CODE

AI CODING TOOLS

quote-check.ts

const response = await fetch("https://attester.dev/v1/symbol/exists", {
  method: "POST",
  headers: { "content-type": "application/json" },
  body: JSON.stringify({
  "type": "http",
  "method": "POST",
  "bodyType": "json",
  "bodyFieldNames": [
    "ecosystem",
    "package",
    "symbol",
    "version"
  ],
  "pathParamNames": [],
  "queryParamNames": []
}),
});

console.log(response.status);
console.log(Object.fromEntries(response.headers));
console.log((await response.text()).slice(0, 1000));

// A valid 402 is a quote, not a completed paid call.

Review the provider input schema before running this non-read-only method. No payment code is included.

JSON ↗developer docs →

STATUS HISTORY

JSON RSS

Observed in cdp-bazaar2026-08-05 04:23 UTC
The registry record was observed and retained with provenance.
Exact route checked2026-08-05 02:58 UTC
not safely testable · potentially-mutating-method:POST
Origin reachable2026-08-05 02:57 UTC
HEAD https://attester.dev/ returned 200.

What evidence supports this listing?

cdp-bazaarobserved 2026-08-05 · open source record ↗

origin checkHEAD https://attester.dev/ → 200 on 2026-08-05

route quotenot invoked automatically · potentially-mutating-method:POST · 2026-08-05

Each record has an exact-route quote outcome. Unresolved templates and potentially mutating methods are labeled instead of being invoked without provider-specific test input. A quote is still separate from a settled paid call. Read the discovery and verification methodology →

Which networks and payment options does it accept?

The normalized listing price is No normalized USD price is recorded. Raw protocol requirements remain visible below for implementation and audit use.

Baseexact5000 atomic · 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913