pay-per-call APIs that agents can actually use.

A discovery proxy for endpoints AI agents need — flight metrics, web search, email lookup. Free tier on every endpoint, no signup. Premium x402 micropayment ($0.001/call) only if you want SLA, batched, or multi-source.

try a live endpoint browse endpoints

# Free tier — no key, no signup, 5 calls/IP/day $ curl -X POST https://agent-marketplace-proxy.vercel.app/try/flight/price-metric \ -H 'content-type: application/json' \ -d '{"origin":"SFO","dest":"NRT","date":"2026-09-15","currency":"USD"}' { "source": "travelpayouts (aviasales affiliate, derived quartiles from month-matrix)", "sample_size": 24, "currency": "USD", "price_metrics": { "p25": 812, "median": 947, "p75": 1184 }, "freshness": "2026-05-17T11:04:00Z" } # Same endpoint, x402-paid — unlimited, SLA, multi-source aggregation $ curl -X POST https://agent-marketplace-proxy.vercel.app/flight/price-metric \ -H 'x402-payment: 0xabc...' \ -d '{"origin":"SFO","dest":"NRT","date":"2026-09-15"}' → 200 OK · $0.001 settled in 84ms

01 what it is

A proxy for the boring APIs AI agents always need.

Agents reach for the same handful of APIs over and over: web search, fare lookup, email lookup, geocoding, weather. We wrap them in agent-friendly shapes (deterministic JSON, no auth handshake, idempotent), expose a free tier on every endpoint so builders can prototype without a card, and gate the high-volume premium tier behind x402 — pay-as-you-go with stablecoins, no SaaS subscription. The endpoints are auto-discoverable via /.well-known/x402.json and listed in the public x402 Bazaar.

02 live endpoints

Endpoints you can curl right now.

Every endpoint has a /try/* free-tier mirror (5 calls per IP per day, no key) and a paid /* production path gated by x402.

POST /flight/price-metric live · $0.001

P25 / median / P75 fare for any origin → destination → date. Returns sample_size so callers can sanity-check thin routes. Source disclosed: Travelpayouts (Aviasales affiliate, derived quartiles).

POST /search live · $0.0008

Web search wrapped in a clean LLM-friendly schema (no scraping garbage, no rate-limit headers to handle). Aggregates Brave + Tavily + Serper behind one envelope.

POST /email/find live · $0.002

Email enrichment: given {name, domain} returns verified work email + confidence + source. For agentic outbound, recruiting agents, CRM enrichers.

POST /email/verify live · $0.0005

SMTP + DNS verification with deliverability score. Built for agents that bulk-validate lists before sending.

GET /.well-known/x402.json discovery

Standard x402 discovery manifest. Drop our domain into any x402-aware agent runtime and the catalog populates automatically. Also indexed in the public x402 Bazaar.

03 two tiers, one surface

Free to try. Paid to scale.

No "talk to sales", no quota tickets, no SDK auth dance. Every endpoint exposes the same JSON shape on the free and premium paths — drop one prefix and you're paying.

Free tier

/try/* · always on

5 calls per IP per day on every endpoint
No API key, no signup, no rate-limit headers
Same JSON shape as premium
Source field always disclosed
Perfect for prototypes & demos

Premium x402

Pay-per-call · no subscription

$0.001 /call (avg)

Unlimited rate, batched-call support
Multi-source aggregation when available
Longer cache windows + freshness header
Settlement on x402 facilitator (USDC, ~80ms)
SLA: 99.5% / 30-day rolling

04 stack & specs

Boringly Vercel. Annoyingly fast.

Runtime	Next.js 14 App Router · edge functions on Vercel · production
Payment rail	`x402` standard · facilitator settles in USDC on Base · ~80ms median settlement
Discovery	`/.well-known/x402.json` · auto-listed in public x402 Bazaar
Cache	Vercel KV · vendor-prefixed keys (no cross-vendor leakage) · 60s default TTL
SDK	`npx agent-marketplace setup` · auto-wires a wallet + endpoint catalog into Cursor / Claude Code / Cline
Source disclosure	Every response carries `source` + `sample_size` fields. No black-box aggregation.
Live URL	`agent-marketplace-proxy.vercel.app` · uptime 99.7% (30d)

05 who uses it

Built for the people wiring agents together.

agent framework devs

Composio / Vapi / browser-use style tool catalogs.

Drop our .well-known into your discovery layer and ship a flight tool, search tool, and email-finder tool without writing three integrations.

x402 builders

Endpoint suppliers for the Coinbase x402 ecosystem.

Listed in the public Bazaar. Reference implementation of "free tier on every endpoint + premium x402" — copy the pattern for your own surface.

indie agent shipping

Solo founders building Cursor / Claude Code workflows.

One npx agent-marketplace setup command wires the wallet + catalog into your runtime. No SaaS dashboard, no team plan.