Shipped: x402 Paid Endpoint Starter Kit — Next.js 16 (now free + MIT)

#solana #python #bitcoin #tutorial

Edit 2026-04-17: This kit is now free + MIT. Source: github.com/cryptomotifs/cipher-x402-mcp. Tip in SOL (cR9KrbsLVJvir5rY9cfY3WeNoxMwUGofzpCoVyobryy) if it saved you time.

Shipped: x402 Paid Endpoint Starter Kit — Next.js 16

After my original x402 paywall walkthrough, the same five questions kept landing in my inbox:

Which version of @x402/next actually works cleanly with the Next.js 16 app router?
Where does the facilitator middleware need to sit so Base mainnet USDC verifies correctly?
Do I need a custom listener to verify the X-PAYMENT header, or does the SDK handle it?
What exact .env variables does a working deploy need?
How do I push this to Vercel without tripping on Node 22 module resolution?

I just packaged the full working answers as a 158 KB starter kit. $15, crypto-direct, no platform middleman.

What's inside the ZIP

Complete Next.js 16 starter repo — no placeholders, this is the code I deploy myself
Pre-wired middleware.ts for the x402 facilitator on Base mainnet USDC
/app/protected/route.ts — the canonical route handler pattern, working end-to-end
.env.example with every variable commented so you know which to set and which are optional
7-page styled tutorial PDF of the original article — nice for offline reading
deploy.sh + deploy.bat — one-command Vercel deploy

How to buy

Three chains, pick whichever you already hold liquidity on:

Chain	Asset	Address
Base / Ethereum / Polygon / Arbitrum / Optimism	USDC	`(removed — see repo)`
Solana	USDC-SPL or SOL	`cR9KrbsLVJvir5rY9cfY3WeNoxMwUGofzpCoVyobryy`
Bitcoin	BTC	`(removed)`

Send (free — MIT on GitHub) to any of the above.
Email the TX hash to **** with subject line (retracted) <chain>:<tx-hash> — e.g. (retracted) base:0xabc123....
ZIP delivered to your inbox, usually within minutes. The verifier matches the TX on-chain, confirms receiver + amount + confirmations, then auto-sends the file via Resend.

Why wallet-direct

I started with Gumroad and Payhip. Both require Stripe or PayPal KYC on the seller side and neither offers a native crypto payout that matches what AI-agent buyers or on-chain customers actually hold. If you're building on x402, your checkout should route the same way your runtime does — to a wallet.

Related (free)

cipher-x402-mcp on GitHub — the MCP server behind the stack, MIT-licensed
cipher-starter — the 12-playbook Solana signal engine write-up the kit grew out of

Questions? Comment here or email. If you hit a gotcha after buying, I'll update the kit and re-send.

Tagged: #x402 #nextjs #ai #crypto #indiedev