API Payments for API Providers

Let AI agents pay as they access your API.

Start Selling to AI Agents View Integration Options

AI AgentRequest protected resource
Request↓
Protected APIPayment required · HTTP 402
↓
Fiat or cryptocurrency payment
↓
Confirmed ReceiptVerified payment result
Request + receipt↓
200 ResponseProtected API returns result

[01]USE CASES

What AI agents can pay to access.

Apply API Payments to endpoints and software-generated resources delivered programmatically.

Paid APIs

Charge for access to a protected endpoint or operation.

Data Access

Sell datasets, search results, or generated reports.

AI Tools

Require payment before an AI agent runs a model, workflow, or specialized tool.

Digital Services

Return paid, software-generated results without a manual purchase step.

[02]how it works

Payment inside the API request flow.

01 ai agent

Request the Resource

The AI agent calls a protected API route.
02 provider

Receive Payment Requirements

The service returns the amount, cryptocurrency, network, and payment destination required for access.
03 ai agent

Complete Payment

The AI agent follows the x402 payment requirements and completes payment using a supported fiat account or cryptocurrency wallet.
04 goat flow

Verify the Result

GOAT Flow verifies the payment and returns a signed payment receipt.
05 ai agent

Retry with the Receipt

The AI agent sends the original request again with the payment receipt attached.
06 provider

Return the Resource

The merchant's middleware verifies the receipt and the API returns the requested result.

[03]what you get

Payment infrastructure for machine-accessed services.

Payment Requirements

Return clear payment information when an AI agent requests a protected resource.

Pay-per-Request Pricing

Set payment requirements for a specific API route or digital resource.

Automatic Payment Verification

GOAT Flow confirms fiat payments through Stripe and cryptocurrency payments on the selected blockchain network before access is provided.

Signed Payment Receipts

Give the protected service a verifiable result tied to the payment and request.

Middleware and Sidecar Options

Protect routes through supported TypeScript or Go middleware, or a language-independent sidecar.

No Checkout Page Required

Keep payment inside the AI agent-to-API request flow.

[04]integration & onboarding

Integrate API Payments in the way that fits your service.

Custom Integration

Best for: Services that want to connect GOAT Flow payments to their existing backend and fulfillment flow.

Setup steps

Complete your GOAT Flow merchant application and configure your cryptocurrency receiving wallet.
Define the paid service and its price.
Use GOAT Flow APIs or server SDKs to create and track the transaction.
Receive the payment result through the API or an authenticated webhook.
Return the result, grant access, or start an asynchronous job from your backend.

MPP Integration

Best for: APIs that want AI agents to complete payment and receive access directly inside the request flow.

Setup steps

Complete your GOAT Flow merchant application and configure your cryptocurrency receiving wallet.
Register the protected API route and its price.
Enable MPP and add a supported middleware or verification sidecar.
Return payment requirements when an AI agent requests the protected resource.
Verify the payment receipt before forwarding the original request to your API.

[05]example flow

See a paid API request from start to finish.

Request

GET /v1/report
Accept: application/json
User-Agent: ExampleAgent/1.0

HTTP/1.1 402 Payment Required
amount: 2.00
currency: USDC
network: selected-network

status: confirmed
payment: verified
receipt: example-receipt
expires: example-expiry

GET /v1/report
Payment-Receipt: example-receipt
Accept: application/json

HTTP/1.1 200 OK
Content-Type: application/json

{ "result": "protected resource" }

Choose each stage to see how the request changes. The example uses placeholder values and never contacts a real API.

[06]payment, fulfillment & trust

A verified payment result before access is returned.

Who is responsible for what

Role	Responsible for
01 API Provider	Defines paid routes, pricing, and response content, and remains responsible for access, availability, and service quality.
02 GOAT Flow	Creates and tracks the transaction, provides x402 payment requirements, receives fiat payment results from Stripe or verifies cryptocurrency payments on the selected blockchain network, and issues a signed receipt or authenticated status update.
03 Stripe	Handles card details, authorization, processing, and settlement for eligible merchants.
04 Blockchain Network	Confirms cryptocurrency payments sent directly to the merchant’s configured wallet and makes the result available for verification.
05 AI Agent	Reads the x402 payment requirements, completes payment using a supported fiat account or cryptocurrency wallet, and retries the original request with the payment receipt.
06 Middleware or Sidecar	Verifies the receipt signature, merchant, route, and expiry before allowing the request to reach the protected API.
07 Webhook Integration	Receives authenticated payment status updates and triggers asynchronous fulfillment when an immediate API response is not required.

API Provider

Defines paid routes, pricing, and response content, and remains responsible for access, availability, and service quality.

GOAT Flow

Creates and tracks the transaction, provides x402 payment requirements, receives fiat payment results from Stripe or verifies cryptocurrency payments on the selected blockchain network, and issues a signed receipt or authenticated status update.

Stripe

Handles card details, authorization, processing, and settlement for eligible merchants.

Blockchain Network

Confirms cryptocurrency payments sent directly to the merchant’s configured wallet and makes the result available for verification.

AI Agent

Reads the x402 payment requirements, completes payment using a supported fiat account or cryptocurrency wallet, and retries the original request with the payment receipt.

Middleware or Sidecar

Verifies the receipt signature, merchant, route, and expiry before allowing the request to reach the protected API.

Webhook Integration

Receives authenticated payment status updates and triggers asynchronous fulfillment when an immediate API response is not required.

[07]NEXT STEPS

Add payment to the API your AI agents already use.

Start Selling to AI Agents Read Developer Documentation