Agent payments

x402 payments for AI agents

Let AI agents pay per API call in USDT and USDC using the x402 standard. Give each agent a spend-capped, self-custodial wallet with per-transaction, daily, and monthly limits and an address allowlist. Machine-speed settlement, human-set boundaries.

Create an accountView the API reference

What is x402?

x402 is a payment standard built on a piece of the web that has existed for decades but was never used: the HTTP 402 "Payment Required" status code. With x402, a server can respond to a request by asking for payment, and the caller pays for that single call before the response is returned. It turns any API endpoint into something that can be metered and paid for per call, in stablecoins, with no accounts, invoices, or card forms.

That matters most for AI agents. An autonomous agent working through a task often needs to call paid APIs, buy data, or use a tool, and it cannot stop to enter a card number. With x402 and a Sendbase wallet, the agent simply pays the 402 challenge in USDT or USDC and continues, all within the spending limits you set.

How it works

How an agent pays with x402

  1. 1

    Give the agent a wallet

    Create a self-custodial Sendbase wallet for the agent with per-transaction, daily, and monthly spend caps.

  2. 2

    Agent calls a paid endpoint

    The endpoint replies with HTTP 402 and the price for that call.

  3. 3

    Agent pays in stablecoins

    Within its limits, the agent pays the amount in USDT or USDC to an allowlisted address.

  4. 4

    The call proceeds

    Payment settles on-chain in seconds, the response returns, and you have a receipt on BscScan.

Why run agent payments on Sendbase

  • Pay per call. x402 meters usage at the request level, so agents pay only for what they use.
  • Hard spend caps. Per-transaction, daily, and monthly limits keep an agent inside a budget you control.
  • Address allowlist. An agent can only pay destinations you approve, closing off unexpected transfers.
  • Self-custodial. The wallet stays yours. You can pause or defund it at any time.
  • Provable. Every agent payment settles on-chain and is verifiable on BscScan.
  • Stablecoins. Agents transact in dollar-pegged USDT and USDC, not volatile assets.

See the full AI agent wallets and the developer API for how to wire it up.

FAQ

x402 payments, answered

A payment standard built on the HTTP 402 Payment Required status code. A server can ask for payment on a request, and the caller, including an AI agent, pays for that single call in stablecoins before the response returns.

You give the agent a spend-capped Sendbase wallet. On a 402 response it pays the requested amount in USDT or USDC within your limits, and the call proceeds. Every payment is on-chain and provable on BscScan.

Each agent wallet has per-transaction, daily, and monthly caps plus an address allowlist. It can only spend within those limits and only pay approved destinations, and the wallet stays self-custodial to you.

BEP-20 USDT and USDC on BNB Smart Chain, which confirms in seconds for a few cents of gas.

Read the full FAQ

Give your agents a wallet

Open a free, self-custodial account and let your agents pay per call with x402.

Create an accountView the API reference