by CoinbaseUS
x402 embeds stablecoin payments in HTTP requests via the HTTP 402 status code. Clients and AI agents send cryptographically signed USDC transfers to request access without accounts, cards, or checkouts.
150M+ transactions. Open standard. Base, Solana, Ethereum, Arbitrum, Polygon.
Updated 2 Apr 2026Checked 10 Oct0 updates this week
Client requests a resource. Server responds HTTP 402 with JSON naming the price in USDC and which blockchains accept it.
Client cryptographically signs a transfer instruction and retries the request with an X-PAYMENT header holding that signature.
Coinbase's CDP facilitator verifies the signature matches the payment terms and broadcasts the signed transfer to the blockchain.
Once the stablecoin transfer is confirmed on-chain, the server responds with HTTP 200 and requested content.
| Spec | x402 payments protocol |
|---|---|
| Transactions processed (as of Sep 2026) | 150M+R (reported) |
| Annualized volume | ~$600ME (estimated) |
| Base blockchain transactions | 119M+R (reported) |
| Solana blockchain transactions | 35M+R (reported) |
| Supported blockchains | Base, Solana, Ethereum, Arbitrum, PolygonR (reported) |
R reported by the company · E our estimate
Coinbase
Crypto exchange, Base L2, custody, derivatives
Largest US crypto exchange, and custodian for most US spot bitcoin ETFs. It built Base, a rollup on Ethereum, shares USDC income with Circle and bought options exchange Deribit in 2025. On Nasdaq since 2021, in the S&P 500 since May 2025.
