x402 census · attester.dev · c6ec73b139d9 · JSON

POST /v1/package/exists

unprobed

Deterministic package existence for PyPI and npm, built from real published artifacts (never LLM guesses). Negative answers and typosquat-adjacency flags carry signed proof. $0.002 USDC per check.

Verdict: not verified by an unpaid GET. not probed yet. This says nothing about whether the route works when called as declared.

Facts from the catalogs

Field Value

URL https://attester.dev/v1/package/exists

Method POST

Price $0.002 USDC = 2000 atomic units of 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913

Network eip155:8453 (base)

payTo 0x57407D691F755cAa107647718F3582a8A87467dD

Seller attester.dev

Catalogs cdp (row updated 2026-09-14)

Listed since (lower bound) 2026-09-14 (earliest catalog timestamp; catalogs report last-update times only)

Last catalog update 2026-09-14

CDP quality counters 1 calls and 1 unique payers in 30 days, last call 2026-09-14 (catalog-reported, not verified on chain)

Category (keyword rule) inference/llm

Templated path no

x402Version in catalog 2

Service name / tags API-existence Oracle: package · oracle, packages, hallucination-check, x402, agents

Unpaid probe (census of )

Field

Value

Probe

not probed in this build

No hourly re-probe has reached this resource yet; the cron covers a rotating slice of 150 per hour.

On-chain facts for the payTo (public address)

Field Value

Distinct payers 5

Payments 7

USDC volume $0.07

Median payment $0.005

First / last payment 2026-07-27 / 2026-09-17

Sampler-shaped share of payments 100.0%

Payers that are not samplers 0

Source forensics-2026-09-30

Address 0x57407D691F755cAa107647718F3582a8A87467dD

Declared input and output (extensions.bazaar)

{
 "input": {
  "body": {
   "ecosystem": "pypi",
   "name": "requests"
  },
  "bodyType": "json",
  "method": "POST",
  "type": "http"
 },
 "output": {
  "type": "json",
  "example": {
   "exists": true,
   "latest_version": "2.32.3",
   "proof": {
    "artifact_sha256": "0x…",
    "source_url": "https://pypi.org/project/requests/"
   },
   "typosquat_adjacent": false
  }
 }
}

Try it (unpaid: shows the 402)

curl -si -X POST 'https://attester.dev/v1/package/exists' -H 'accept: application/json' -H 'content-type: application/json' --data '{}'

The catalog declares POST. A 402 answer carries the payment requirements in the JSON body and, for x402 v2, base64 in the PAYMENT-REQUIRED header. This page never sends a payment.

Paid checks (x402, USDC on Base)

GET https://bazaar.agentexchange.work/r/c6ec73b139d9/probe.json re-runs this probe right now for $0.01 and writes the result here. POST https://bazaar.agentexchange.work/featured with {"id":"c6ec73b139d9"} places this resource at the top of the report and search pages for 30 days for $1.00, labelled. Unpaid requests answer 402 with the terms. Pricing.

Catalog references: agentic.market (CDP Bazaar front end) · this record as JSON · all resources on attester.dev.