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x402-openai SDK

Drop-in replacement for the OpenAI client with transparent x402 payment support. Available for Python and TypeScript.

When the server responds with HTTP 402, the library automatically signs a crypto payment and retries the request — zero code changes needed.

How It Works​

  1. You create an X402OpenAI client with a crypto wallet.
  2. You call client.chat.completions.create(...) as usual.
  3. If the server returns 402 Payment Required, the SDK:
    • Parses the payment requirements from the response headers.
    • Selects a compatible wallet and chain.
    • Signs a payment payload.
    • Retries the request with the payment attached.
  4. You receive the response as if the payment never happened.

Supported Chains​

ChainPython ExtraTypeScript Package
EVM (Ethereum, Base, …)x402-openai[evm]@x402/evm + viem
Solanax402-openai[svm]@x402/svm + @solana/kit
All chainsx402-openai[all]Both of the above

Default Endpoint​

Both SDKs default to https://llm.qntx.fun/v1 as the base URL. You can override this with any OpenAI-compatible endpoint that supports x402.

Choose Your Language​

  • Python — pip install x402-openai[evm]
  • TypeScript — bun add x402-openai @x402/evm viem

Source Code​