Topic · 6 insights · 3 how-tos
x402 Payments: How AI Agents Pay in USDC
x402 is an open protocol that turns HTTP's long-unused 402 Payment Required status into a way to pay for a web resource. A server answers an unpaid request with 402 and a price; the client, often an AI agent, signs a USDC authorization and retries; a facilitator settles the payment on-chain and the server returns the resource.
In SpendTheBits your @handle is an x402 seller. You publish a priced resource, agents pay it in USDC, and each settled call lands in your wallet as an ordinary inbound transaction. The same app can also pay x402 resources on your behalf. We measured our first live exchange at 1.4 seconds from the 402 to settled USDC on Base.
- Payment token: USDC, signed with EIP-3009 transferWithAuthorization, so the payer needs no gas.
- Seller URLs: x402.spendthebits.com/@handle/slug/.
- Discovery: /.well-known/x402, /llms.txt and /openapi.json list public resources.
- Settlement: through a facilitator (Coinbase CDP; Circle for Arc).
Insights
· 7 min read
What is x402? The x402 protocol for AI agent payments
Discover the x402 protocol, an open standard built on HTTP 402 that enables seamless, account-free payments for software and autonomous AI agents.
· 8 min read
x402 Payments in Production: What It Costs to Get Paid by an AI Agent
x402 payments measured in production: 1.4 s from HTTP 402 to settled USDC on Base, who pays gas, what the facilitator charges, and how replays are refused.
· 7 min read
AI agent payments in production: an agent bought a gift card over x402, with no custodian
How AI agent payments work without a custodian: an agent bought a real gift card over x402, paid in USDC, through a contract that only forwards or refunds.
· 7 min read
How to monetize an API with x402 without custody
Learn how to monetize an API natively using the open-source x402 protocol, stateless HTTP headers, and non-custodial wallets.
· 7 min read
EIP-3009 transferWithAuthorization explained
Learn how EIP-3009 transferWithAuthorization enables gasless stablecoin payments with random nonces and why the x402 standard uses it.
· 7 min read
x402 on Arc: agent payments with final settlement
Discover how x402 on Arc enables automated software tools to settle payments in real time with absolute finality and low costs.
How-to guides
- How to get paid by AI agents with x4026 min · step by step
- How to pay an x402 API from your wallet4 min · step by step
- How to let your AI agent buy a gift card5 min · step by step
In the product: Get paid by AI agents
Try it with your own keys.
SpendTheBits is a fully non-custodial wallet, free on iOS and Android.