402.md
>_ SKILL.md

Your API Is Already Built.
Now Make It Pay.

SKILL.md is the agent-readable spec that replaces every SDK you'd have to maintain. Register once — 94K+ AI agents discover your API, pay with USDC, and call it automatically. You ship nothing new.

Generate My SKILL.mdSee a Live Example
0+Transactions
$0+Volume
0+Agents
0+Developers
x402.md protocol stats
>_ The Standard

Think of It as a package.json for the Agent Economy

Traditional SDKs have a problem: you write them, maintain them, version them, and distribute them — and most developers never install them.

SKILL.md is different. It's a single Markdown file with YAML frontmatter that tells any AI agent everything it needs: what your API does, how much it costs, how to pay, and how to call it.

No client library. No npm package. No versioning headaches.

Agents read your SKILL.md. They pay via x402. They call your API. You get settled in USDC.

Traditional SDK
  • → Write client library
  • → Publish to npm/PyPI
  • → Version & maintain
  • → Market to developers
  • → Handle auth & billing
SKILL.md SDK
  • → Write one .md file
  • → Register on 402.md
  • → Edit in 30 seconds
  • → Auto-listed in Bazaar
  • → x402 handles payment
SKILL.md
 1---
 2name: my-api
 3version: 1.0.0
 4description: What your API does, in plain text.
 5  Agents read this and know if they need you.
 6skill_token: skt_abc123
 7base_url: https://api.example.com
 8price_per_call: "0.050000"
 9currency: USDC
10payment_network: base
11endpoints:
12  - path: /v1/analyze
13    method: POST
14    description: Core endpoint agents call
15    price: "0.050000"
16x402:
17  payment_address: "0xYourWallet"
18  hold_period: 0
19  settlement_frequency: daily
20---
21
22# My API
23
24One paragraph. What it does, who it's for,
25what agents get back. That's all you need.
>_ The Transformation

Four Steps from API to Revenue

Your existing API doesn't change. You just give agents a way to find it, understand it, and pay for it.

You Have an API

REST, GraphQL, whatever. It already works. Nothing changes in your backend — no new routes, no new auth, no new infra.

// Your existing API
POST /v1/analyze
Content-Type: application/json

{ "text": "analyze this" }
→ 200 OK { "sentiment": "positive" }

Write a SKILL.md

Add YAML frontmatter to a Markdown file. Set your price, endpoints, and wallet address. 402.md generates one for you in the dashboard.

# In your dashboard
npm create skill@latest

→ SKILL.md generated
→ price: $0.05/call
→ skillToken: skt_abc123

Agents Discover You

Your skill auto-registers in Coinbase Bazaar — the index 94K+ AI agents query when they need capabilities. No marketing required.

// Agent queries Bazaar
GET /discovery/search
  ?q=sentiment+analysis

→ your-skill returned
→ SKILL.md fetched by agent

Agents Pay. You Earn.

Agent reads your SKILL.md, pays $0.05 via x402, calls your endpoint, gets the result. 97% settles to your wallet. No invoice.

// x402 flow (automatic)
POST /v1/analyze → 402
X-PAYMENT: <proof>
POST /v1/analyze → 200

→ $0.0485 settled to you
>_ Why SKILL.md

The SDK You Never Have to Ship

No SDK to Maintain

Traditional SDKs need updates every time your API changes. SKILL.md is a spec file — edit it in 30 seconds, agents get the new version automatically.

Auto-Listed in Bazaar

Every registered skill appears in Coinbase Bazaar — the discovery index AI agents query. No marketing, no app store approval. Register and be found.

Payment Built into the Protocol

Agents receive a 402 Payment Required response, pay with USDC on Base, and retry — all automatically. You write zero payment code.

Keep 97% of Every Call

3% platform fee. No per-seat licensing, no rev share tiers, no chargeback risk. Daily USDC settlements direct to your wallet address.

>_ SDK vs SKILL.md

You've Shipped an SDK Before.
This Is Better.

Dimension
Traditional SDK
SKILL.md
Development time
Days to weeks
~15 minutes
Maintenance
Ongoing — new versions, changelogs
Edit one file. Done.
Distribution
npm, PyPI, GitHub releases
Auto-listed in Bazaar on register
Agent discovery
SEO, word of mouth, hope
94K+ agents search Bazaar
Payment integration
Build it yourself (weeks)
x402 is built in — zero code
Revenue model
API keys + billing infrastructure
Pay-per-call, automatic settlement
>_ Start Now

Your API Could Be Earning
While You Sleep

Sign up, register your skill, paste your API spec. 402.md generates your SKILL.md and registers it in Bazaar. First agent payment typically arrives within 24 hours.

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