5 new verified APIs on PayAPI Market

By Chet Parker · Published 2026-09-28 · Last updated September 28, 2026 · 3 min read

Since the 25 Sep post we have paid to verify another batch of 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. Verified means we paid.

Each card below names the one route we paid for. Other routes a provider offers are not covered by that check.

The APIs

Invoice-OCR API

Turns an uploaded invoice or receipt into structured JSON: vendor, amount, date and line items.

• Provider: Synthexforge
• Price: $0.02 per request
• Verified route: POST /v1/invoice-ocr
• Settlement: 0x5ed63ebe2533… on Base
• Listing: https://payapi.market/api/invoice-ocr-api

Penny Press

Short essays and fragments, free for humans, a few cents per read for machines.

• Provider: Penny Press
• Price: $0.01 per request
• Verified route: GET /essays/big-stakes
• Settlement: 0xe0ff5e780db1… on Base
• Listing: https://payapi.market/api/penny-press

x402 Market Index (P0)

A ranked report of paid x402 services by 30-day calls, paying wallets and price, rebuilt from the Coinbase x402 Bazaar feed.

• Provider: P0
• Price: $0.02 per request on the verified route
• Verified route: GET /report
• Settlement: 0x05a14c29fbc8… on Base
• Listing: https://payapi.market/api/x402-market-index-p0

Duet CSV Preflight

Checks a CSV before import: row widths, missing required values, duplicate rows and keys, stray whitespace and formula-like cells.

• Provider: Astra Duet
• Price: $0.005 per request
• Verified route: POST /v1/preflight
• Settlement: 0xa83d13104d45… on Base
• Listing: https://payapi.market/api/duet-csv-preflight

crosscheck

Reviews an agent's draft before a human sees it and returns a structured verdict with a signed receipt.

• Provider: crosscheck
• Price: $0.02 per request on the verified route
• Verified route: POST /v1/check
• Settlement: 0x74ad3cab26df… on Base
• Listing: https://payapi.market/api/crosscheck-independent-review-of-an-agent-s-draft

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/get?id=duet-csv-preflight"

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

The current catalogue

After this morning's badges the catalogue is 231 APIs and 2788 endpoints. The homepage number updates on the next production build. Do not treat an older blog snapshot as current.

For the live count at any time, see https://payapi.market/llms.txt

Connect an agent

Discovery is free. Agents search the catalogue here. Payment happens on the listing 402, not on PayAPI.

{
  "mcpServers": {
    "payapi": {
      "url": "https://payapi.market/mcp"
    }
  }
}