API Paywall Cookbook: Open source x402 examples for production-ready monetized APIs

Also available in Português and Español.

Building a monetized API shouldn't require reading extensive documentation and reverse-engineering integration patterns. You need working code you can deploy and adapt immediately.

What is the API Paywall Cookbook?

The API Paywall Cookbook is an open-source collection of production-ready examples showing how to monetize APIs using the x402 protocol. Each example runs in production, demonstrating real implementations you can study and deploy.

The project covers multiple programming languages and complexity levels:

Beginner examples:

• Deep Thought API (Node.js/Hono) — Reference implementation
• Vulcan Logic API (Go/Gin) — Production Go implementation

Intermediate examples:

• Extract Wisdom API (Node.js/Hono) — AI-powered YouTube content extraction

Advanced examples:

• Socratic Mentor API (Bun/Hono) — Mini-ledger with optimistic payment flow
• Oracle of Babel (Rust) — Algorithm-as-a-Service

From hello world to sophisticated monetization

The cookbook starts with minimal "hello world" examples to verify the basics, then progresses to sophisticated patterns like LLM wrappers that handle dynamic per-token pricing.

You'll find implementations in Node.js, Bun, Go, Rust, and Python (coming soon). Each example demonstrates a specific x402 pattern, from simple request-based pricing to advanced optimistic payment flows with mini-ledgers.

Zero-code integration with God Mode

One standout feature is the "God Mode" transparent proxy, which lets you monetize existing APIs without modifying their code. Kobaru handles the x402 protocol layer while your API logic remains unchanged.

This approach works across blockchains (Solana, Base, SKALE) and supports both per-request and dynamic pricing models.

Testing x402 APIs

The repository includes the 007 Test Agent, a universal command-line tool for testing any x402 API. You can verify payment flows, authorization handling, and settlement processes before deploying your own implementation.

Built for production

These aren't toy examples. Each API runs in production with real payment processing. You can call them, inspect their responses, and see how they handle payment verification and settlement.

The cookbook serves three purposes: production testing of x402 implementations, practical learning beyond basic documentation, and demonstrating how straightforward API monetization can be.

Ready to implement? Check out the API Paywall Cookbook repository and the Kobaru documentation for integration details.