How do I install the Ekx X402 skill?

Run npx skillmds@latest add ekinoxis-evm/ekx-x402 in your terminal (requires Node.js), paste this page's agent-chat prompt into Claude, Cursor, or any MCP-connected agent, or download the SKILL.md file and copy it into your agent's skills directory.

Is Ekx X402 safe to use?

This skill has not completed SkillMD's automated safety review yet. Capability flags: makes network calls, reads secrets. SkillMD never runs a skill's scripts for you; review the SKILL.md before installing.

Which AI agents work with Ekx X402?

This skill is tagged as working with Claude Code, Claude.ai, OpenAI Codex. SKILL.md is an open format, so most agents that read a skills directory can load it too.

Is Ekx X402 free to use?

Yes. Installing skills from SkillMD is free, and the skill stays under its author's original license.

Who published Ekx X402?

Ekinoxis-evm (@ekinoxis-evm) published this skill. Their other Agent Skills are listed on their SkillMD profile.

Ekx X402 by ekinoxis-evm — Agent Skill

Name: Ekx X402
Rating: 4.5 (4 reviews)
Author: Ekinoxis-evm

Ekx X402

The x402 HTTP payment standard — charging for API access with HTTP 402, USDC settlement on Base, buyer and seller SDKs, facilitators, and agent-to-agent payments. Use when building a paid API endpoint, when an agent needs to pay per request, or when integrating the Bazaar discovery layer.

Ekinoxis-evm Updated Sep 22, 2026

File contents

x402

Pay-per-request HTTP payments settled in USDC on Base.

Alchemy's endpoint: https://x402.alchemy.com · Coinbase facilitator: https://api.cdp.coinbase.com/platform/v2/x402

This file records our position on it, not the protocol spec.

The idea

A server responds 402 Payment Required with a PAYMENT-REQUIRED header describing price and network. The client signs a USDC payment, retries with PAYMENT-SIGNATURE, and gets the resource. Settlement is ~1 second on Base, no protocol fee, no account.

Headers: PAYMENT-REQUIRED → PAYMENT-SIGNATURE → PAYMENT-RESPONSE. Networks are CAIP-2: Base mainnet is eip155:8453, Base Sepolia eip155:84532. Schemes: exact (fixed price) or upto (usage-based, EVM only).

Why it matters to us

It is the only clean answer to "how does an autonomous agent pay for something?" No API key to provision, no subscription, no human in the loop. That maps directly onto a P2P agent and any future Ekinoxis agent product.

It is early. Treat it as a bet, not infrastructure — build the paid endpoint so that x402 is one payment path among others, not the only door.

Seller (Next.js)

import { paymentMiddleware } from "@x402/next";

export const middleware = paymentMiddleware(
  process.env.DESTINATION_WALLET!,       // where USDC lands
  { "/api/score": { price: "$0.01", network: "eip155:8453" } },
  { url: "https://api.cdp.coinbase.com/platform/v2/x402" },   // facilitator
);

Buyer

import { wrapFetchWithPayment } from "@x402/fetch";
const paidFetch = wrapFetchWithPayment(fetch, walletClient);
const res = await paidFetch("https://api.example.com/score");

Rules we apply

Cap spend per agent run. A buyer wallet with an unbounded loop and a paid endpoint is a money leak with no error message. Budget per session and hard-stop.
Testnet first — eip155:84532 with faucet USDC (../ekx-circle-usdc/SKILL.md).
Settlement is not delivery. Verify PAYMENT-RESPONSE before treating the resource as paid for; log both sides for reconciliation.
The receiving wallet is a hot wallet. Sweep to treasury; do not accumulate.
Price in USDC, 6 decimals. "$0.01" = 10000 units.

Related: ../ekx-tempo/SKILL.md — MPP is the same idea on Tempo.

---name: ekx-x402description: The x402 HTTP payment standard — charging for API access with HTTP 402, USDC settlement on Base, buyer and seller SDKs, facilitators, and agent-to-agent payments. Use when building a paid API endpoint, when an agent needs to pay per request, or when integrating the Bazaar discovery layer.---# x402Pay-per-request HTTP payments settled in USDC on Base.Alchemy's endpoint: `https://x402.alchemy.com` · Coinbase facilitator:`https://api.cdp.coinbase.com/platform/v2/x402`This file records *our* position on it, not the protocol spec.---## The ideaA server responds `402 Payment Required` with a `PAYMENT-REQUIRED` header describingprice and network. The client signs a USDC payment, retries with `PAYMENT-SIGNATURE`,and gets the resource. Settlement is ~1 second on Base, no protocol fee, no account.Headers: `PAYMENT-REQUIRED` → `PAYMENT-SIGNATURE` → `PAYMENT-RESPONSE`.Networks are CAIP-2: Base mainnet is `eip155:8453`, Base Sepolia `eip155:84532`.Schemes: `exact` (fixed price) or `upto` (usage-based, EVM only).---## Why it matters to usIt is the only clean answer to *"how does an autonomous agent pay for something?"*No API key to provision, no subscription, no human in the loop. That maps directlyonto a P2P agent and any future Ekinoxis agent product.It is **early**. Treat it as a bet, not infrastructure — build the paid endpoint sothat x402 is one payment path among others, not the only door.---## Seller (Next.js)```tsimport { paymentMiddleware } from "@x402/next";export const middleware = paymentMiddleware( process.env.DESTINATION_WALLET!, // where USDC lands { "/api/score": { price: "$0.01", network: "eip155:8453" } }, { url: "https://api.cdp.coinbase.com/platform/v2/x402" }, // facilitator);```## Buyer```tsimport { wrapFetchWithPayment } from "@x402/fetch";const paidFetch = wrapFetchWithPayment(fetch, walletClient);const res = await paidFetch("https://api.example.com/score");```---## Rules we apply1. **Cap spend per agent run.** A buyer wallet with an unbounded loop and a paid endpoint is a money leak with no error message. Budget per session and hard-stop.2. **Testnet first** — `eip155:84532` with faucet USDC ([`../ekx-circle-usdc/SKILL.md`](../ekx-circle-usdc/SKILL.md)).3. **Settlement is not delivery.** Verify `PAYMENT-RESPONSE` before treating the resource as paid for; log both sides for reconciliation.4. **The receiving wallet is a hot wallet.** Sweep to treasury; do not accumulate.5. **Price in USDC, 6 decimals.** `"$0.01"` = `10000` units.Related: [`../ekx-tempo/SKILL.md`](../ekx-tempo/SKILL.md) — MPP is the same idea on Tempo.

Frequently asked questions