x4PayAPI Market · Marketplace

Pay-per-call APIs for AI agents

Best x402 APIs for AI agents (2027 list)

1045 live APIs · 1034 settlement-verified. 6318 endpoints in total. AI agents discover via MCP and pay per request in USDC on Base, Solana or Algorand. Like the browsable grid, the rows below show settlement-verified listings only.

Verification

  • $0.003 /x402/v1/mail-auth/stripe.com · ipv4.fr email authentication check · SPF, DMARC policy and common DKIM selectors of a domain, with findings and a verdict. Maintained by ipv4.fr. · 1 route verified
  • $0.01 /v1/services/agent.trust-badge {"agent_name":"BlindOracle"} · BlindOracle · Counterparty-risk infrastructure for agent-to-agent commerce: agent reputation lookup, trust badges, pre-hire checks… · 1 route verified
  • $0.001 /v1/email-check {"emails":["jane.doe@gmial.com"]} · MailCheck API · Email and domain validation for agents by Rowan Vale (built with AI assistance). POST /v1/email-check validates up to… · 1 route verified

See all Verification

Finance

  • $0.02-1.5 /v1/brief/NBIS · BeliefState · Cited investor research for AI agents: stock theses, risks, catalysts, revisions and historical cutoffs. 16 research… · 1 of 18 routes verified
  • $0.002 /api/currency · Agent Extraction API: Currency conversion (ECB reference rates) · Currency conversion with official ECB euro reference rates (~30 currencies, daily). Params: from, to, amount. Also… · 1 route verified
  • $0.1 /api/pack · Money Reactor 24h All-In Trial Pass · 24h unlimited calls on every micro-price route - pay once, send X-DAY-PASS header instead of signing every call. The… · 1 route verified

See all Finance

Data

  • $0.01 /is-workday · China Calendar & ID Check API · Mainland China holidays/调休, lunar calendar, 24 solar terms, USCC & resident ID checksum. 0.01 USDC/call on Base via… · 1 of 7 routes verified
  • $0.1 /search · Indo News Keyword Search · Search Indonesian news (Google News Indonesia) by keyword and get up to 25 deduped articles as JSON: title, source… · 1 route verified
  • $0.005 /x402/v1/asn/15169 · ipv4.fr AS number lookup · Holder, country and registry of an autonomous system, with the prefixes it announces. Maintained by ipv4.fr. · 1 route verified

See all Data

Tools

  • $0.01 /timestamp · x402-seller · Pay-per-call x402 utilities on Base USDC: GET /timestamp (ISO UTC clock) and POST /echo. $0.01 per request. Durable… · 1 route verified
  • $0.1 /api/defi-yields · Money Reactor DeFi Yield Scanner (stablecoins) · Deterministic agent utility on Base. Always-deliver guarantee, real-time response, settled in USDC via x402. Pay one… · 1 route verified
  • $0.005 /v1/https-cert-preflight · Public HTTPS Certificate Preflight · Read-only public TLS certificate preflight: expiry, not-before, hostname match and CA authorization from a pinned… · 1 route verified

See all Tools

Intelligence

  • $0.09 /tiebreaker (provider example body) · Tiebreaker · Tiebreaker provides Autonomous Agents with Human Level Reasoning and Decision Making through a proven decision… · 1 route verified
  • $0.1 /api/store/market-report · Money Reactor Instant Store: Agent Economy Field Report (Oct 2026) · INSTANT DELIVERY - 30 days of first-hand autonomous-agent earning data: 12-platform status map, CDP Bazaar demand scan… · 1 route verified
  • $0.001-0.00123 /v1/chat/completions · Laminarity Relay · OpenAI-compatible LLM inference (DeepSeek, GLM, MiniMax). Pay per request in USDC via x402, no signup or API keys. · 1 of 3 routes verified

See all Intelligence

Live listings that we have not paid for yet are not hidden, only unselected by default: browse every live listing, verified and not.

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Frequently asked questions

How does an agent pay for an API here?

Call the provider's endpoint unpaid. It replies HTTP 402 with the price, wallet and network. Your agent signs a USDC payment authorisation, retries the request with the signed payment attached, and gets the response. No API key or account is needed. Discovery is free; payment only happens when your agent calls a provider directly.

What does settlement-verified mean?

It means PayAPI Market paid a real call on one specific route from its own wallet, got real product back, and there is an on-chain USDC receipt that anyone can check, on Base for most routes. It is not a health ping. Verification covers the route we paid, not the whole listing: a listing with 10 routes and one paid route reads 1 of 10 routes settlement-verified.

Do I need an API key?

No. The payment is the authentication. Your agent signs a per-call USDC payment, and the provider's endpoint validates it. There is no account, API key, OAuth flow or signup. The agent needs a wallet holding USDC on Base, but no keys from any individual provider.

How much does it cost to use an API?

Each provider sets its own price per call, shown on the listing. Prices start at fractions of a cent, and the exact USDC amount arrives in the 402 challenge before any money moves. There are no subscriptions, minimums or monthly fees. Your agent pays only for the calls it makes, in USDC on Base, and you can cap spend by funding a dedicated wallet with a bounded balance.