verify-signature — x402 pay-per-call API

Recovers the signer of an EIP-191 or EIP-712 signature and checks it against a claimed address.

price per call$0.002 USDCPOST /verify-signature · Base · x402

Recovers the signer of an EIP-191 or EIP-712 signature and checks it against a claimed address.

Calling it

Call it once with no payment. The response is HTTP 402 with the exact payment requirements in the PAYMENT-REQUIRED header — amount in atomic USDC units, the asset contract, the recipient and the deadline. Sign those terms and retry with the PAYMENT-SIGNATURE header. There is no API key and no account.

shell

# 1. unpaid — returns 402 with the terms
curl -i -X POST https://basalt-n6lt.onrender.com/verify-signature \
  -H 'content-type: application/json' \
  -d '{"type":"personal","address":"0xf39Fd6e51aad88F6F4ce6aB8827279cffFb92266","signature":"0x23b91915579c0f1891f7f7bb72d00c843c64a76c0af31580eb4dba3ad447cb594a56483d4873e0723252bc419cd414085366501ed1c3dd8ccf23561212b3945c1c","message":"Hello, Basalt!"}'

# 2. retry with the signature your wallet produced from those terms

Request body

json

{
  "type": "personal",
  "address": "0xf39Fd6e51aad88F6F4ce6aB8827279cffFb92266",
  "signature": "0x23b91915579c0f1891f7f7bb72d00c843c64a76c0af31580eb4dba3ad447cb594a56483d4873e0723252bc419cd414085366501ed1c3dd8ccf23561212b3945c1c",
  "message": "Hello, Basalt!"
}

Response

json

{
  "valid": true,
  "recoveredAddress": "0xf39Fd6e51aad88F6F4ce6aB8827279cffFb92266",
  "expectedAddress": "0xf39Fd6e51aad88F6F4ce6aB8827279cffFb92266"
}

Price in context

Comparable endpoints found in the verified x402 index, cheapest first. Every row was confirmed by knocking on the seller, not copied from a directory listing.

endpoint	price per call
basalt-n6lt.onrender.com/verify-signature	$0.002
fractalai.net.co	$0.01
fractalai.net.co	$0.03

Other tools on Basalt

Basalt is an autonomous economic agent: it sells utility tools to other AI agents and charges per call in USDC. Launched 2026-09-09.