x4PayAPI Market

x402 roundup: 2 Nov to 8 Nov 2026

Since 2026-11-04 we paid to verify 20 new APIs on PayAPI Market. Here are five of them, and what each verification actually proved.

What "verified" means here

We do not take a provider's word for it. For every API on this list we sent a real payment in USDC on Base, from our own wallet, and checked that the response contained genuine data.

Each check uses an input the provider did not advertise, so a canned example response cannot pass. Where the underlying data is public, we compare the paid response against the original source field by field.

The APIs

Call when an agent needs an exact pascal and bar conversion

Call when an agent needs an exact pascal and bar conversion. psi returns 404 because the published NIST factor is not marked exact.

  • Provider: agentshield.live
  • Price: $0.002 per request
  • Verified route: GET /pressure?value=1&unit=bar
  • Settlement: 0x01f5878018a9… on Base

CrawlSafe

Check if a URL may be crawled: RFC 9309 robots.txt for your user agent, plus X-Robots-Tag/meta robots. SSRF-guarded on every redirect hop.

  • Provider: PromptShield
  • Price: $0.002 per request
  • Verified route: POST /v1/check
  • Settlement: 0x4748e927e5e9… on Base

Call when an agent needs an exact litre, cubic metre, and imperial gallon

Call when an agent needs an exact litre, cubic metre, and imperial gallon conversion. The US gallon returns 404.

  • Provider: agentshield.live
  • Price: $0.003 per request
  • Verified route: GET /volume?value=1&unit=gal_uk
  • Settlement: 0xa7b6d4e87fc2… on Base

Call when an agent needs an exact newton and pound-force conversion from the

Call when an agent needs an exact newton and pound-force conversion from the published NIST footnote. Not the rounded table row.

  • Provider: agentshield.live
  • Price: $0.003 per request
  • Verified route: GET /force?value=1&unit=lbf
  • Settlement: 0x56a5abf1c678… on Base

PromptShield Clean

HTML to LLM-ready text cleaner for agents. 0.002 USDC on Base via x402.

  • Provider: PromptShield
  • Price: $0.002 per request
  • Verified route: POST /v1/clean
  • Settlement: 0x48b17ea8f02d… on Base

How an agent finds these

Every verified API is queryable as JSON. An agent does not need to read this post, or the website, to find them.

curl "https://payapi.market/agent/list"
curl "https://payapi.market/agent/search?q=property"

Those endpoints return only live listings, and by default only ones we have paid to verify.

The current catalogue

PayAPI Market lists 2671 live APIs, of which 1475 are settlement-verified, across 5 categories: Data, Finance, Intelligence, Tools, Verification.

By · Published 2026-11-12 · Last updated November 12, 2026 · 2 min read