attester.dev package exists

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

payable

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.

We sent a real POST request to this endpoint and it answered 402 with payment requirements we could parse.

Price: $0.002
Network: base
Pay to: 0x57407D691F755cAa107647718F3582a8A87467dD
Spec dialect: v2 (declares x402Version 2)
Transport: PAYMENT-REQUIRED header
HTTP method: POST
Response latency: 1070 ms
Payment options: 1 usable of 1
Last checked: 2026-08-10T09:09:48.817Z (1d ago)
Category: ai-inference

Re-check it yourself:
curl "https://api.the402.dev/validate?url=https%3A%2F%2Fattester.dev%2Fv1%2Fpackage%2Fexists"