HTTP 402

For decades, HTTP 402 Payment Required has been reserved for future use. x402 unlocks it, and absolves the internet of its original sin.

What is HTTP 402?

HTTP 402 is a standard, but rarely used, HTTP response status code indicating that payment is required to access a resource.

In x402, this status code is activated to:

• Inform clients (buyers or agents) that payment is required.

• Communicate the details of the payment, such as amount, currency, and destination address.

• Provide the information necessary to complete the payment programmatically.

Why x402 Uses HTTP 402

The primary purpose of HTTP 402 is to enable frictionless, API-native payments for accessing web resources, especially for:

• Machine-to-machine (M2M) payments (e.g., AI agents).

• Pay-per-use models such as API calls or paywalled content.

• Micropayments without account creation or traditional payment rails.

Using the 402 status code keeps x402 protocol natively web-compatible and easy to integrate into any HTTP-based service.

Summary

HTTP 402 is the foundation of the x402 protocol, enabling services to declare payment requirements directly within HTTP responses. It:

• Signals payment is required

• Communicates necessary payment details

• Integrates seamlessly with standard HTTP workflows