Next.js Crypto Payments: Server-Side Integration with Paychainly API Routes

Project Structure

app/
├── api/
│   ├── payment/
│   │   ├── create/route.ts      # POST — create session
│   │   └── webhook/route.ts     # POST — receive webhook
│   └── payment-status/
│       └── [sessionId]/route.ts # GET — poll status
├── pay/
│   └── page.tsx                 # Payment UI

Create Session Route

// app/api/payment/create/route.ts
import { NextRequest, NextResponse } from 'next/server';

export async function POST(req: NextRequest) {
  const { orderId, amount } = await req.json();

  const res = await fetch('https://paychainly.com/api/v1/addresses/start-session', {
    method: 'POST',
    headers: {
      'x-api-key': process.env.PAYCHAINLY_API_KEY!,
      'Content-Type': 'application/json',
    },
    body: JSON.stringify({ userId: String(orderId), amount }),
  });

  const session = await res.json();
  return NextResponse.json(session);
}

Webhook Route

// app/api/payment/webhook/route.ts
import { createHmac, timingSafeEqual } from 'crypto';

export async function POST(req: NextRequest) {
  const raw = await req.text();
  const payload = JSON.parse(raw);
  const sig = req.headers.get('x-signature') ?? '';

  const msg = [payload.event, payload.txHash, payload.fromAddress,
    payload.toAddress, payload.amount, payload.blockNumber,
    payload.timestamp, payload.userId].join('|');

  const expected = createHmac('sha256', process.env.PAYCHAINLY_WEBHOOK_SECRET!)
    .update(msg).digest('hex');

  if (!timingSafeEqual(Buffer.from(sig), Buffer.from(expected))) {
    return NextResponse.json({ error: 'Unauthorized' }, { status: 401 });
  }

  // Process payment...
  return NextResponse.json({ ok: true });
}

Environment Variables

# .env.local
PAYCHAINLY_API_KEY=your_key
PAYCHAINLY_WEBHOOK_SECRET=your_secret