HTTP 402 - Payment Required

HTTP 402 "Payment Required" is a status code reserved in the HTTP protocol specification for future use in digital payment systems, representing the intersection of web infrastructure and financial transactions.

What It Is

HTTP 402 is one of the standard HTTP response codes, sitting alongside familiar codes like:

• 200 (OK)
• 404 (Not Found)
• 500 (Internal Server Error)

However, unlike these widely-used codes, 402 was reserved but never fully implemented in the original web.

Original Intent

When the HTTP protocol was designed, 402 was intended to signal: "You must pay to access this resource."

Why It Matters Now

With the rise of:

• Micropayments
• AI-to-AI commerce
• Programmable money
• Cryptocurrency payment rails

HTTP 402 is being revisited as a potential standard for enabling seamless payments embedded directly in web requests.

How It Could Work

1. Client requests a resource (API call, content, service)
2. Server responds with 402 + payment details
3. Client automatically processes payment
4. Client re-requests with proof of payment
5. Server delivers the resource

Use Cases

• API Monetization: Pay per request rather than subscription
• Content Access: Micropayments for individual articles or data
• AI Agent Commerce: Machines negotiating and paying for services
• Compute Resources: Pay only for resources actually consumed

Current Status

While not yet a universal standard, various implementations are emerging:

• Lightning Network payments (Bitcoin)
• Stablecoin micropayments
• HTTP 402-inspired APIs
• Protocol proposals like Web Monetization

Significance for AI Agents

HTTP 402 provides a standardized way for autonomous systems to discover payment requirements and execute transactions without human intervention—essential for machine commerce at scale.