X402

Skill aiskillstore/marketplace/skills/internet-court/x402

x402 agentic payments using Coinbase's HTTP 402 protocol. Provides custody-free tools to pay x402-protected endpoints by building the EIP-3009 transferWithAuthorization payload, signing it, and assembling the X-PAYMENT header; call facilitator verify, settle, and supported operations; and monetize APIs by generating PaymentRequirements. Supports USDC on Base. Use for x402, HTTP 402, pay-per-request, agentic or machine payments, X-PAYMENT, transferWithAuthorization, EIP-3009, facilitators, API monetization, and agents paying for APIs.From its SKILL.md

Install

npx -y skills add aiskillstore/marketplace --skill x402

Assembled from the repository path, not quoted from the project. Check it against their README if it does not work.

One thing to look at

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SKILL.md

2.8 KB, 617 tokens by cl100k_base, as published. Nobody here has run it

x402 Payments skill

x402 turns HTTP 402 Payment Required into a real payment rail for agents: a server replies 402 with what it wants paid; the client signs an off-chain authorization and retries with an X-PAYMENT header; a facilitator broadcasts it. Settlement uses EIP-3009 transferWithAuthorization (e.g. USDC on Base) — the facilitator can only broadcast the signed authorization, never alter the amount or destination.

Custody-free: the plugin builds the EIP-712 the payer signs and assembles the header; it never holds a key.

Tools

Tool	Purpose
`chaingpt_x402_decode`	Decode a 402 body or X-PAYMENT header into human terms (amount/token/recipient/expiry) before paying.
`chaingpt_x402_build_payment`	Build the UNSIGNED EIP-3009 typed data; pass a signature back to get the final `X-PAYMENT` header.
`chaingpt_x402_facilitator`	Call a facilitator: `supported` / `verify` / `settle`.
`chaingpt_x402_create_requirements`	Server side: generate the `PaymentRequirements` + 402 body to monetize your endpoint.
`chaingpt_x402_fetch`	The whole client loop in one tool: fetch a URL; on 402 it decodes the challenge and (given `from`) emits the unsigned typed data; re-call with `xPaymentHeader` to complete the paid request.

Pay an endpoint (client flow)

Fast path — one tool drives the loop:

chaingpt_x402_fetch url=<resource> from=<payer> → on 402 you get the decoded price/payee AND the unsigned EIP-3009 typed data.
Sign the typed data in the payer's wallet.
chaingpt_x402_build_payment from=<payer> requirements=<from step 1> signature=0x… → the X-PAYMENT header.
chaingpt_x402_fetch url=<resource> xPaymentHeader=<header> → the paid response.

Manual path (same primitives, finer control): _decode → _build_payment → sign → _build_payment +signature → retry yourself.

Monetize your endpoint (server flow)

chaingpt_x402_create_requirements network=base amount=0.01 payTo=<you> → serve the returned JSON with HTTP 402. Verify/settle incoming payments via a facilitator (chaingpt_x402_facilitator).

Known EIP-3009 tokens: USDC on base and base-sepolia. For other tokens pass full PaymentRequirements (with asset + extra.name/extra.version). 0 ChainGPT credits.

What ships with it: 1 file

9.1 KB alongside SKILL.md

skill-report.json9.1 KB