x402-fiber-sdk

Add CKB Fiber payments to any Node.js API in under 10 minutes.

import { fiberPaywall } from '@x402-fiber/express'

app.get('/data', fiberPaywall({ price: '0.001 CKB' }), handler)

That's it. Your route now responds with HTTP 402, generates a Fiber invoice, verifies payment, and unlocks the response — automatically.

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What this is

x402 is a Linux Foundation protocol (April 2026) that operationalises HTTP 402 for machine-to-machine payments. Coinbase, Stripe, Cloudflare, Visa, Mastercard, Google, and AWS are all building for it.

Every existing x402 implementation settles on Base (Ethereum). Minimum payment: ~$0.01.

CKB Fiber settles in milliseconds with zero channel fees. Minimum payment: $0.0001. This SDK brings x402 to Fiber — the only rail where true micropayments are economically viable.

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Status

In active development. This SDK is being built in public. Follow progress in Discussions.

• @x402-fiber/core — invoice generation, payment verification, settlement
• @x402-fiber/express — Express middleware adapter
• @x402-fiber/hono — Hono middleware adapter
• @x402-fiber/next — Next.js route handler adapter
• @x402-fiber/client — client-side fetch wrapper (auto pay + retry)
• Live demo endpoint on funded Fiber mainnet node

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How it works

1. Client requests a resource
   GET /api/data

2. Server responds: payment required
   HTTP 402
   { "invoice": "fibt1...", "amount": "0.001", "asset": "CKB" }

3. Client pays via Fiber channel
   sendPayment(invoice)  →  ~340ms, zero fees

4. Client retries with payment proof
   GET /api/data
   X-Payment: <proof>

5. Server verifies and responds
   HTTP 200 OK + data

No accounts. No subscriptions. No humans in the loop.

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Why Fiber

	x402 on Base	x402 on Fiber
Min viable payment	~$0.01 (gas)	$0.0001 (zero channel fees)
Settlement speed	~2 seconds	Milliseconds
Multi-asset channels	No	Yes (CKB, USDI, ccBTC, RGB++ assets)
Works for $0.001 micropayments	No	Yes

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Prior work

This SDK grew out of Fiber-402 — a proof-of-concept built for the Claw and Order: CKB AI Agent Hackathon (March 2026). The hackathon demo showed the full x402 flow working end-to-end with an AI agent. This repo is the next step: turning that proof-of-concept into a reusable SDK any developer can drop into their project.

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Dev logs

Progress is documented weekly in Discussions.

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Run the demo locally

git clone https://github.com/David-Pjs/fiber402
cd fiber402
npm install

Create .env.local:

ANTHROPIC_API_KEY=your_key

# Optional: connect a real Fiber node
# FIBER_NODE_RPC_URL=http://127.0.0.1:8227

npm run dev

Open http://localhost:3000. Without a Fiber node, payments fall back to mock automatically.

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Built on CKB Fiber Network. Implementing the x402 protocol.