v0.6.2  ·  built by null

Agents can't sign up
for APIs.

x402 is a payment standard for machines — no signups, no API keys, just USDC. x402-mcp is the MCP server that makes it usable: 957 live paid APIs, discoverable and payable in a single tool call from any agent.

Start free View catalog →
npx @nullbuilds/x402-mcp  ·  no signup required  ·  works with Claude, Cursor, Windsurf
Claude — x402-mcp
▸ x402_discover({ keyword: "weather" })
6 live APIs · Base network
x402-data-bazaar.vercel.app/api/weather 0.002 USDC
vibesprings.net/api/v1/.../weather 0.002 USDC
vibesprings.net/api/v1/.../historical 0.004 USDC
▸ x402_pay({ url: "x402-data-bazaar.vercel.app/..." })
✓ Paid 0.002 USDC · 142ms
{ "temp_f": 72.4, "condition": "Clear",
"humidity": 58, "wind_mph": 7 }
▌
957
Live APIs
13,334
Endpoints tested
Nightly
Catalog updated
7.2%
Survival rate
of probed endpoints are live
Works with
Claude
Cursor
Windsurf
any MCP client
Quickstart

Up in 30 seconds.

No account. No API key. Add one block to your MCP client config and start browsing 957 live paid APIs immediately — no wallet required.

claude_desktop_config.json  ·  mcpServers
"x402": {
  "command": "npx",
  "args": ["-y", "@nullbuilds/x402-mcp"]
}
discover + estimate work immediately  ·  add CDP wallet config to enable payments
How it works

Discover, estimate, pay.

Three tools. No configuration required for the first two. Add a hosted wallet for the third.

01  /  DISCOVER

Browse 957 live APIs

Filter by keyword or network. FDA alerts, FX rates, Twitter intelligence, and more — all x402-enabled.

02  /  ESTIMATE

Check the cost first

Probe any endpoint live. See the exact price before committing a single cent. No payment made.

03  /  PAY

One call. Payment handled.

Signing happens in Coinbase's TEE via CDP Server Wallets. Your private key never touches your machine.

Before / After

One call, not five.

Raw x402 means probing the 402, parsing payment requirements, signing EIP-3009, encoding the header, and retrying. x402-mcp collapses it to a single tool call.

Without x402-mcp
// 1. Probe the 402
const probe = await fetch(url);
// 2. Parse payment requirements
const req = parseX402(probe);
// 3. Sign EIP-3009 transfer
const sig = await signEIP3009(wallet, req);
// 4. Encode payment header
const hdr = encodeHeader(sig);
// 5. Retry with payment
const res = await fetch(url, {
  headers: { 'X-PAYMENT': hdr }
});
With x402-mcp
// Just ask Claude.

"Call the weather API for SF,
 max $0.01"

// x402-mcp handles everything.

✓ Paid 0.008 USDC · Response returned
Pricing

Free forever.
0.5% when you pay.

Install and use x402-mcp with no cost, no signup, no credit card. When we launch hosted wallets, we take 0.5% of what your agent spends. That's it. No monthly fees. No seats. No tiers.

✓Catalog access — free
✓Cost estimation — free
✓BYOW (bring your own CDP wallet) — free
◎Hosted wallet — coming soon
$0
to start
+ 0.5% on agent
payments via
hosted wallet
hosted wallet: coming soon

Hosted wallet  ·  coming soon

No CDP setup. No key management. Add x402-mcp and your agent can pay immediately. Get notified when it launches.

No spam. One email when hosted wallet ships.
FAQ
Do I need a crypto wallet to use this?
No. x402_discover, x402_estimate, and x402_balance all work with zero credentials. You only need a wallet to make actual payments via x402_pay.
Is my private key on my machine?
No. Payments use Coinbase CDP Server Wallets — signing happens in Coinbase's TEE. Your private key never touches your device.
How is the catalog kept up to date?
A cron job probes all 13,334 registered x402 endpoints every night. Only the ones that respond correctly with a valid 402 payment schema are included. The 7.2% survival rate is real.
What MCP clients does this work with?
Any MCP client: Claude Desktop, Cursor, Windsurf, and anything else that supports the Model Context Protocol. Configure once, works everywhere.