Turn APIs intopaid servicesfor AI agents.

Specimen
402
Payment Required
Price
0.0100 USDC
Ledger
awaiting proof
CHG 7F3A 21C9 0410
Specimen. One paid request, from challenge to settlement. Figures are illustrative.

BUIDL is a merchant console and gateway proxy for agentic payments. Create paid URLs, verify agent payment proofs, settle charges, configure payouts, and send signed webhook events without changing your origin API.

Changes to your origin API
None
Unpaid request receives
HTTP 402 challenge
Each settled payment creates
Charge, ledger credit, webhook

Agents pay before your origin handles the request.

Gateway sits in front of the merchant origin. It presents payment options, validates agent payment proof, settles the charge, emits webhooks, and forwards the request only when the payment path succeeds.

Transcripts are abridged and illustrative.

  1. 1

    Agent calls the Gateway URL

    Gateway resolves the workspace, endpoint, method, price, network, and origin from the public URL.

    GET /m/workspace/endpoint HTTP/1.1Host: gateway.buidlbnb.io
  2. 2

    Gateway asks for payment

    The response tells the agent which payment options are accepted for that endpoint, in a machine-readable challenge.

    HTTP/1.1 402 Payment RequiredContent-Type: application/json{ "accepts": [{ "scheme": "exact",    "asset": "USDC", "maxAmountRequired": "…" }] }
  3. 3

    Payment proof is verified

    The agent retries with payment proof. Gateway validates it before the origin sees the request.

    GET /m/workspace/endpoint HTTP/1.1X-PAYMENT: eyJ4NDAyVmVyc2lvbiI6MSwic2NoZW1l…
  4. 4

    Origin response is returned

    Settlement creates a charge, credits the merchant ledger, and sends subscribed webhook events.

    HTTP/1.1 200 OKX-PAYMENT-RESPONSE: eyJzdWNjZXNzIjp0cnVl…ledger  credit  charge.succeeded

Set a wallet, define a threshold, and reconcile claims.

Settled charges credit the merchant ledger. Payout policy controls define when balances are reserved and sent to the configured destination wallet, and every claim is tracked to paid or failed.

  • Balances are computed from settled ledger entries
  • Threshold policies reserve balances before transfer
  • Destination, network, asset, and claim state are tracked
  • Payout webhooks report paid and failed outcomes
Statement of account
Workspace acme-data, Live mode, amounts in USDC
Specimen
DescriptionDebitCreditBalance
charge.succeeded /m/acme/weather0.010024.9600
charge.succeeded /m/acme/weather0.010024.9700
charge.succeeded /m/acme/forecast0.025024.9950
charge.succeeded /m/acme/forecast0.025025.0200
Payout claim reserved at threshold25.02000.0000
charge.succeeded /m/acme/weather0.01000.0100
Closing balance0.0100
Opening balance brought forward 24.9500. Specimen statement. References, endpoints, and figures are illustrative, not customer data.

Questions before putting an API behind BUIDL.

Practical details about the gateway flow, console records, payouts, webhooks, supported rails, and mode separation.

Any HTTP endpoint with a reachable origin URL. You configure the origin, allowed methods, price, and status; BUIDL gives you a paid Gateway URL for agents to call.

Gateway responds with a machine-readable payment challenge for the endpoint. The agent retries with payment proof, and Gateway verifies it before forwarding to your origin.

BUIDL settles the payment through the selected rail, streams the origin response, records a charge, credits the merchant ledger, stores proof details, and emits subscribed webhook events.

Settled charges appear in the merchant ledger. Payout policies define destination, asset, network, and threshold, while payout claims show requested, processing, paid, failed, or cancelled state.

No. x402 is one supported machine-payment rail. The product is a gateway layer so merchants can expose paid APIs to agents without rebuilding endpoint, ledger, payout, and webhook operations for each protocol.

Endpoints, charges, revenue, average charge, failure rate, latency, top endpoints, top payers, payout state, webhook endpoints, and webhook delivery results.

Use Test mode to configure and validate endpoint behavior without mixing it into Live reporting. Live mode is for production endpoints, charges, analytics, and payout activity.

Start from the console. Create an endpoint first.

The first useful action is creating a paid proxy in front of an existing HTTP origin, then testing the payment challenge and retry loop.