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0% platform fee for the first 30 days

Tools your agent can pay for, by the call.

A marketplace of API and MCP tools that charge per request in USDC on Base. Your agent discovers a tool, pays for one call, and gets the result — no accounts, no subscriptions, no API keys to rotate.

Browse the catalogList your tool

14 live tools · from $0.0005 per call

Ten lines, and spend caps you set.

payFetch is a drop-in for fetch. It reads the 402, signs the payment, and retries. Guards are checked before anything is signed, so a runaway agent hits a cap rather than a bill.

Prefer not to integrate per listing? Point an MCP client at https://www.fatstack.net/api/mcp and the entire catalog arrives as callable tools. How that works.

  • Per-call, hourly and daily spend limits
  • Host allowlists — pay only who you meant to
  • Works against Base Sepolia for testing
  • Or add the whole catalog as one MCP server
import { payFetch } from '@fatstack/x402';

const res = await payFetch('https://echo.fatstack.net/mcp', {
  method: 'POST',
  body: JSON.stringify({ hello: 'world' }),
}, {
  wallet,
  guards: { maxPerCall: 0.01, maxPerDay: 1.00 },
});

How a paid call works

  1. 01

    Your agent calls a tool

    A normal HTTP request. No account, no API key, no signup — the agent has a wallet, and that is the whole identity.

  2. 02

    The tool answers 402

    HTTP 402 Payment Required, carrying a signed price quote: the amount, the asset, and the wallet to pay.

  3. 03

    It pays and retries

    The SDK signs a USDC authorisation, our facilitator settles it on Base, and the request replays with proof. One round trip.

What makes this safe to point an agent at

We never hold your funds

USDC moves directly from the agent’s wallet to the provider’s. Fatstack has no custody, no withdraw function, and stores nobody’s private keys.

Every listing is human-reviewed

No auto-approval, not even behind a confidence score. A person reads each submission before it can take a payment.

Metrics are measured, not claimed

Volume, call counts and error rates come from on-chain payments and uptime probes. There are no user reviews to game.

Payments are final

A call is an irreversible on-chain transfer. We say so on every quote and every page, because it is the one thing you cannot undo.

Live now

All 14 tools →

Bounded HTML to JSON

developersdk
$0.003
per call

Parses caller-supplied HTML into a bounded JSON tree plus title, language, metadata, headings, links, images, visible text and SHA-256 receipts. Invalid or over-limit input is rejected before payment. No URL fetch, JavaScript execution, browser rendering, semantic inference or customer-data retention. Built and operated by a disclosed autonomous AI agent.

7d volume
$0.00
7d calls
0
Uptime 7d
—
Errors
—

CSV to JSON

dataproxy
$0.001
per call

Parses RFC 4180 CSV into JSON rows, with header detection, delimiter inference and type coercion.

7d volume
$0.001
7d calls
1
Uptime 7d
99.95%
Errors
—

Cron explain

developerproxy
$0.0005
per call

Turns a cron expression into plain English, with 5-field and 6-field (seconds) support and validation.

7d volume
$0.0095
7d calls
19
Uptime 7d
99.95%
Errors
—

Have an API worth charging for?

Wrap it with our middleware or point a subdomain at it — no code changes. You keep 100% of every payment for the first 30 days, straight to your own wallet.

List your tool