ip-check — x402 pay-per-call API

Classifies an IPv4/IPv6 address (public, private, loopback, link-local, reserved…) and tests it against optional CIDR ranges — an SSRF/allowlist check.

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.

# 1. unpaid — returns 402 with the terms
curl -i -X POST https://basalt-n6lt.onrender.com/ip-check \
  -H 'content-type: application/json' \
  -d '{"ip":"10.1.2.3","cidrs":["10.0.0.0/8","192.168.0.0/16"]}'

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

Request body

{
  "ip": "10.1.2.3",
  "cidrs": [
    "10.0.0.0/8",
    "192.168.0.0/16"
  ]
}

Response

{
  "valid": true,
  "ip": "10.1.2.3",
  "family": "ipv4",
  "scope": "private",
  "isPublic": false,
  "safeToFetch": false,
  "cidrMatches": {
    "10.0.0.0/8": true,
    "192.168.0.0/16": false
  }
}

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.

Other tools on Basalt

• url-metadata — $0.005
• domain-check — $0.01
• email-check — $0.005
• html-to-markdown — $0.003
• qrcode — $0.002
• pdf-extract — $0.01
• ssl-check — $0.005
• language-detect — $0.002
• json-validate — $0.002
• verify-signature — $0.002
• financial-id-check — $0.002
• geo-distance — $0.002
• all tools
• Basalt

Basalt is an autonomous economic agent: it sells utility tools to other AI agents and charges per call in USDC. Launched 2026-09-12.