How does HTTP 402 differ from x402?

HTTP 402 is the status code itself, while x402 is a specific protocol implementation that defines how to use HTTP 402 in practice. x402 provides standardized headers, payment challenge formats, and receipt verification for HTTP 402 flows.

When should I use HTTP 402?

Use HTTP 402 when you want to monetize API access, enable pay-per-use models, or implement micropayments for content or services. It's particularly useful for agent-to-agent commerce, API marketplaces, and premium content access.

HTTP STATUS CODE

HTTP 402 Payment Required

Q: What is HTTP 402 Payment Required?

HTTP 402 Payment Required is a standard HTTP status code reserved for digital payment systems. It indicates that payment is required to access the requested resource. When a server returns 402, it signals to the client that a payment must be made before the request can be fulfilled.

The HTTP status code reserved for digital payment systems. Learn how to implement payment-required responses for API monetization and agent commerce.

What is HTTP 402?

HTTP 402 Payment Required is a standard HTTP status code that was originally reserved for future use in digital payment systems. It indicates that payment is required to access the requested resource.

When a server returns a 402 response, it signals to the client that the request cannot be fulfilled without payment. The response typically includes information about the payment amount, currency, and payment methods accepted.

While HTTP 402 has been part of the HTTP specification since HTTP/1.1, it remained largely unused until recent interest in API monetization and agent-to-agent commerce revived its purpose.

How HTTP 402 works

Client requests a resource - The client makes an HTTP request to a protected endpoint
Server returns 402 - The server responds with HTTP 402 Payment Required, including payment details in the response body
Client makes payment - The client processes the payment through the specified payment method
Client retries with proof - The client retries the original request with a payment receipt or proof of payment

Basic HTTP 402 response

HTTP/1.1 402 Payment Required
Content-Type: application/json
Cache-Control: no-store

{
  "error": "Payment required",
  "message": "Access to this resource requires payment",
  "amount": "0.10 USD"
}

HTTP 402 vs x402

HTTP 402

The HTTP status code itself. Part of the HTTP/1.1 specification.

Standard status code
No specific format
Implementation-agnostic

x402

A protocol specification for implementing HTTP 402 in practice.

Standardized headers
Payment challenge format
Receipt verification

Use cases for HTTP 402

API Monetization

Charge for API access on a per-request or subscription basis. Enable pay-per-use pricing models.

Agent Commerce

Enable autonomous agents to discover pricing and pay for services automatically.

Content Paywalls

Protect premium content behind payment requirements with verifiable receipts.

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