Documentation
Documentation
Welcome to OpenUSDC. The gateway is open-source middleware that speaks the x402 standard; the SDKs let your agents pay any x402 endpoint in USDC. Start with the Quickstart, then dig into the API reference and language-specific SDK guides.
Get started in 5 minutes
The fastest way to see OpenUSDC in action is to run the gateway locally with the deterministic sandbox chain, then hit it from any HTTP client. The Quickstart walks you through it end-to-end.
# Install the CLI
npm i -g @openusdc/cli
# Run the gateway in sandbox mode
openusdc dev --chain sandbox --route POST:/echo --price "0.0010 USDC"
# In another terminal:
openusdc fetch POST http://localhost:7202/echo --max-spend "0.01 USDC"Within seconds you should see a signed payment receipt printed to stdout. From there it's a small step to swap --chain sandbox for --chain base with a real USDC-funded wallet.
Concepts
The x402 standard
HTTP 402 has lived in the spec since the 90s as the "Payment Required" response. The x402 payment standard formalizes how a server quotes a price and how a client pays it — using a small set of HTTP headers and a stablecoin settlement.
The gateway
The OpenUSDC gateway is a middleware layer for Node, Python, Go, Rust, Deno, and Cloudflare Workers. It intercepts requests to a priced route, returns a 402 with the price quote when payment is missing, validates payment headers, settles on-chain, and forwards the request to your handler with a signed receipt attached.
The SDK
The OpenUSDC SDK is what an agent (or a plain client) uses to pay. It wraps a wallet, signs x402 payment headers, retries 402 responses automatically, and emits structured receipts your code can persist alongside business state.
OpenUSDC Cloud
Cloud is the optional hosted control plane — the dashboard, webhook fanout, reconciliation ledger, alerts, and exports. It is wire-compatible with the self-hosted gateway and entirely opt-in.
Pick a path
Where to start depends on which side of the request you sit on.
- You're building an agent → Quickstart → SDKs → For agent developers
- You're putting an API behind x402 → Quickstart → Gateway API reference
- You're operating finance → For finance teams → Webhooks reference