Skip to main content
Prefer credits and sponsor grants. Get started For the lowest-friction web2/web3 UX, keep users on credits or sponsor grants by default. Use x402 when a payment-aware API, MCP, or agent client receives a 402 quote and can retry with a receipt. x402: API returns 402 with a quote → pay → retry with PAYMENT-SIGNATURE.

​
Where 402 appears

FlowWhen
POST /api/v1/verificationNo credits
GET /api/v1/proofs/checkNo credits
MCP toolsNo credits
Hosted-adjacent billable callsNo credits on the paying party

​
Steps

  1. Call API.
  2. Receive 402 + quote.
  3. Pay.
  4. Retry with PAYMENT-SIGNATURE: <receipt>.

​
Surfaces

Verification, gate checks, hosted billable calls, and agent delegation with payments:x402 can use the same pattern. 
PAYMENT-SIGNATURE: <receipt>

Get started

Credits first.

Billing

Who pays.

Hosted Verify

Hosted flows.

MCP

MCP + x402.

Agent delegation

payments:x402.