x402Relay
228 APIs indexed — Phase 1: Discovery Live

x402Relay — AI Agents Find and Use APIs Instantly

228 verified x402-enabled APIs in one catalog. AI agents discover, compare Trust Scores, and pay with USDC — no API keys, no accounts, just HTTP 402.

Browse the CatalogRead the Docs
x402r-cli
# Search the Hub Directory from terminal
$ x402r search --query "translation" --category "ai"

┌──────────────┬──────────┬───────┬─────────┐
│ Name         │ Category │ Trust │ Price   │
├──────────────┼──────────┼───────┼─────────┤
│ TranslateX   │ ai       │ 92    │ $0.001  │
│ LangBridge   │ ai       │ 87    │ $0.002  │
└──────────────┴──────────┴───────┴─────────┘

# Or via MCP — AI agent connects directly
mcp: search_services({ query: "translation" })
→ 2 verified services found

For API Providers

List your x402-enabled API on the Hub Directory. x402scan verifies your endpoint and assigns a Trust Score, so AI agents discover and trust your service.

Explore Features

For Agent Builders

Give your AI agents discovery superpowers. Search the Hub Directory via MCP, CLI, or SDK to find verified x402 APIs instantly.

See How It Works

Quickstart

Search APIs in 3 steps

1Install
npm install @x402-relay/sdk
2Config
x402-relay proxy --upstream localhost:3000 --price 0.001
3Detail
x402r detail <serviceId>
# endpoint, price, trust score
Full Docs

The Problem

APIs Weren’t Built for AI Agents

Today’s API economy relies on human-centric authentication and billing. As AI agents become autonomous, this model breaks down.

API Keys Everywhere

Every API requires a unique key, separate registration, and manual management. AI agents can’t autonomously acquire new API access.

Billing Account Overhead

Credit cards, invoices, payment methods — each provider has its own billing system. Impossible for autonomous agents to navigate.

Manual Setup Required

Sign up, verify email, add payment method, generate keys, configure SDKs. A process designed for humans, not machines.

No Discovery

AI agents have no way to find new APIs on their own. Every service URL must be hardcoded by a human. The agentic economy can’t scale without autonomous discovery.

How It Works

How x402Relay Works

A simple, three-step HTTP flow that turns any API into a pay-per-use service — no API keys needed.

1
Search

Search APIs

Use natural language or structured queries to find x402-enabled APIs in the Hub Directory.

x402r search --query "translation"
2
Verify

Compare Trust Scores

x402scan verifies every endpoint. Compare uptime, response time, and compliance scores.

Trust: 92 | Uptime: 99.9%
3
Pay

Sign, Pay, Get Response

Agent signs a USDC payment authorization, resends the request with proof, and receives the API response after on-chain settlement.

Payment-Signature: 0x... -> 200 OK

Integration

Agentic Wallets by Coinbase

Powered by Coinbase Developer Platform (CDP), agentic wallets give AI agents their own crypto wallets with programmable spending controls.

AI Agent

Autonomous Task

Agentic Wallet

Coinbase CDP

x402 Payment

Sign & Send

API Access

Get Response

Autonomous API Discovery

Agent discovers new APIs, evaluates pricing from 402 responses, and pays on-demand — no pre-registration needed.

Budget-Controlled Spending

Set spending limits per agent, per task, or per time period. Wallet enforces constraints on-chain.

Multi-Agent Collaboration

Multiple agents share a single wallet or operate independent wallets. Each transaction is auditable on-chain.

Why x402Relay

Start Free with Coinbase. Get Chosen by AI Agents with x402Relay.

Coinbase provides the payment rails. x402Relay builds the marketplace where AI agents actually find and choose your API.

FeatureCoinbase CDPx402Relay
Hub Directory (Verified Catalog)—✓
x402scan (Trust Score)—✓
MCP Server (5 Tools)—✓
CLI (x402r)—✓
Intent Search (NLP)—✓
Basic Payment (verify/settle)✓✓
USDC on Base✓✓
Free Tier✓✓

Being discoverable by AI agents is the new competitive advantage. Join the waitlist to list your API on the Hub Directory.

Components

Everything You Need to Discover & Trust APIs

x402Relay provides a complete stack — from the Hub Directory where AI agents discover services, to x402scan that verifies every endpoint.

Hub Directory

The verified API catalog for AI agents. Search by keyword, category, or natural language. Available via REST API, MCP, and CLI.

x402scan

Automated discovery engine that crawls GitHub, probes endpoints for x402 compliance, and assigns Trust Scores (0–100).

MCP Server

5 built-in tools let AI agents search services, get details, check status, list categories, and get intelligent recommendations — all programmatically.

TypeScript SDK

x402Client handles 402 responses, EIP-3009 signing, and retries automatically. Drop-in replacement for fetch().

CLI (x402r)

Search the catalog from your terminal. 6 commands with pipe-friendly JSON output — perfect for automation and agent toolchains.

Use Cases

Built for the Agentic Economy

From micro-payments to premium data feeds — x402 enables new business models for the AI era.

Translation

AI Translation API

Charge $0.001 per translation request. AI agents pay per-call with USDC — no subscription needed.

POST /translate -> 402 -> Pay $0.001 USDC -> Get translation
Data

Premium Data Feeds

Sell real-time market data, weather feeds, or analytics. Micro-payments make premium data accessible to any agent.

GET /market/BTC -> 402 -> Pay $0.01 USDC -> Get live price
MCP

MCP Server Billing

Monetize Model Context Protocol servers. Charge per tool call so LLMs pay for external capabilities on demand.

MCP tool call -> 402 -> Pay $0.005 USDC -> Execute tool

Developer Experience

Terminal to Agent — One Catalog

Search the catalog from CLI, connect via MCP, or integrate with the SDK. Every path leads to verified x402 APIs.

CLI — x402r
terminal
# Install the CLI
$ npm install -g @x402relay/cli

# Search for AI APIs
$ x402r search --query "image generation" --limit 5
┌────────────┬──────────┬───────┬─────────┐
│ Name       │ Category │ Trust │ Price   │
├────────────┼──────────┼───────┼─────────┤
│ ImageForge │ ai       │ 88    │ $0.01   │
└────────────┴──────────┴───────┴─────────┘

# Get details (pipe-friendly JSON)
$ x402r detail svc-123 --json | jq .endpoint
"https://imageforge.example.com/v1"
SDK — AI Agent
client.ts
// client.ts — AI Agent discovers and calls APIs
import { x402Client } from "@x402-relay/sdk"

const client = x402Client({
  walletProvider: agentWallet,  // Coinbase Agentic Wallet
})

// Works just like fetch() — handles 402 automatically
const response = await client.fetch(
  "https://api.example.com/translate",
  {
    method: "POST",
    body: JSON.stringify({ text: "Hello" }),
  }
)
const data = await response.json()
// Payment handled transparently!

Roadmap

Building the Future of Machine Payments

From testnet prototype to production-ready infrastructure for the agentic economy.

Phase 1Live

Discovery (Current)

  • Hub Directory — verified API catalog
  • x402scan — automated discovery & Trust Score
  • MCP Server (5 tools)
  • TypeScript SDK & CLI (x402r)
  • REST API + Intent Search
Phase 2Coming Soon

Custodial Payments

  • pay_and_call — agents send URL + budget, Relay pays
  • Payment history & subscription plans
  • Verification Tier 2/3 (testnet & mainnet audit)
  • External Facilitator integration (Coinbase CDP)
Phase 3Planned

Multi-Chain & Ecosystem

  • Solana support (Ed25519, SPL USDC)
  • LangChain / AutoGen / CrewAI integration
  • Anthropic MCP official catalog registration
  • Self-hosted Facilitator on Base

FAQ

Frequently Asked Questions

Get Early Access

Ready to Build the Agentic Economy?

Join the waitlist to get early access to x402Relay. List your API on the Hub Directory and get discovered by AI agents.

DocsGitHubx402 Spec