x402ai

AI microservices monetized via the x402 payment protocol — pay-per-request with on-chain USDC, no accounts, no API keys, no KYC.

Live at api.x402ai.dev · Base mainnet

Overview

x402ai exposes a set of AI inference endpoints behind a native HTTP 402 payment wall. Each request is individually priced and settled on-chain via EIP-3009 token authorization. The service is self-hosted on a home server and served publicly through a Cloudflare Zero Trust tunnel.

Pricing is fixed per endpoint. Live prices are always available at GET /health.

Endpoints

Payment Flow

x402ai implements the x402 protocol over standard HTTP. No wallet registration or pre-authorization required.

Client                          Server                        Facilitator (Coinbase CDP)
  │                               │                                    │
  │  POST /api/embed              │                                    │
  │ ─────────────────────────────►│                                    │
  │                               │                                    │
  │  402 Payment Required         │                                    │
  │  X-Payment-Details: { price,  │                                    │
  │    network, recipient, ... }  │                                    │
  │◄─────────────────────────────-│                                    │
  │                               │                                    │
  │  [client signs EIP-3009       │                                    │
  │   transferWithAuthorization]  │                                    │
  │                               │                                    │
  │  POST /api/embed              │                                    │
  │  X-Payment: <signed payload>  │                                    │
  │ ─────────────────────────────►│                                    │
  │                               │  verify + settle on-chain         │
  │                               │ ──────────────────────────────────►│
  │                               │                                    │
  │                               │  settlement confirmed              │
  │                               │◄───────────────────────────────────│
  │                               │                                    │
  │  200 OK + inference result    │                                    │
  │◄──────────────────────────────│                                    │

Key properties:

• Each request carries its own signed payment authorization
• The Coinbase CDP facilitator verifies and settles the USDC transfer on-chain
• No session state, no subscriptions, no trust required from the client

Architecture

                    ┌─────────────────────────────────────┐
                    │         api.x402ai.dev               │
                    │   Cloudflare Zero Trust Tunnel       │
                    └──────────────────┬──────────────────┘
                                       │ HTTPS
                    ┌──────────────────▼──────────────────┐
                    │         Hono (Node.js)               │
                    │         x402-hono middleware         │
                    │                                      │
                    │   /api/embed  →  Ollama              │
                    │   /api/summarize  →  Ollama          │
                    │   /api/ask  →  Ollama                │
                    │   /health  →  status + pricing       │
                    └──────────────────┬──────────────────┘
                                       │
                    ┌──────────────────▼──────────────────┐
                    │              Ollama                  │
                    │   nomic-embed-text (768-dim)         │
                    │   qwen3.5-nothink:2b                 │
                    └─────────────────────────────────────┘

                    Hardware: Dell Precision, Intel i7-6700

Payment settlement runs on Base mainnet via the Coinbase CDP facilitator.

Stack

Why x402?

HTTP 402 ("Payment Required") has been reserved since 1996 but never standardized. The x402 protocol finally makes it practical: a server returns a 402 with machine-readable payment instructions, the client signs an EIP-3009 authorization over the exact amount, and a facilitator settles it on-chain. The server only processes the request after settlement is confirmed.

The result is a fully permissionless API economy — no OAuth, no billing dashboards, no rate-limit tiers. Just sign and pay.

License

MIT