Building Lightning Payments with Spark

Want to add Lightning payments to your app but don't want to run a node? This presentation demonstrates integrating Lightning payments using Spark, a developer-friendly protocol that abstracts away channel management and node operation. We'll walk through the Spark Soundboard demo app, showing real code and integration patterns to get you building quickly.

Most developers want to add Lightning payments without becoming Lightning experts. Spark provides: • Simple API - no channel management, no liquidity concerns • Fast integration - from zero to Lightning payments in minutes • Lower barrier to entry - no node operation required • Focus on app logic - not Lightning network topology Tradeoff: Spark is self-custodial (you hold your keys), but it's a Layer 2 protocol with different trust assumptions than running your own Lightning node. Spark handles the Lightning channels and liquidity management for you, which simplifies development but introduces additional protocol-level trust.

The Spark Soundboard is a Lightning-enabled soundboard that charges 100 sats per sound effect: **User Flow:** 1. User clicks a sound button (airhorn, drumroll, tada, or crickets) 2. Backend creates Lightning invoice using Spark SDK 3. QR code modal appears with the invoice 4. User pays with any Lightning wallet 5. Backend polls wallet transfers every 3 seconds to detect payment 6. Frontend polls payment status every second 7. When payment confirmed, sound plays automatically **Tech Stack:** • Node.js + Express backend • Vanilla HTML/CSS/JavaScript frontend • @buildonspark/spark-sdk for wallet and invoices • qrcodejs for QR code generation • In-memory payment tracking (Map) No login required, no database needed - just Lightning payments and sound effects.

The Spark Soundboard demonstrates a complete Lightning payment flow: **Backend (Node.js + Express):** • Initialize Spark wallet using @buildonspark/spark-sdk • Create Lightning invoices via sparkWallet.createLightningInvoice() • Poll for payment confirmation by checking wallet transfers every 3 seconds • Store pending payments in-memory (Map) • Serve static frontend files **Frontend (Vanilla HTML/CSS/JS):** • Display sound buttons (airhorn, drumroll, tada, crickets) • Generate QR code for invoice using qrcodejs library • Poll backend for payment status • Auto-play sound when payment confirmed **Key Integration Points:** 1. Wallet initialization with mnemonic phrase 2. Invoice creation (100 sats per sound) 3. Payment monitoring via sparkWallet.getTransfers() 4. Payment status polling (frontend checks every second) Check the GitHub repo for the complete source code.

Ready to integrate Lightning payments with Spark? 1. Review the Spark Soundboard code for real-world examples 2. Check Spark documentation for API details and SDK setup 3. Start with a simple proof-of-concept in your app 4. Test with small amounts on testnet first 5. Iterate and refine based on user feedback Remember: Spark is one tool in the Lightning ecosystem. As you grow, you can migrate to self-sovereign Lightning if needed. Start simple, ship fast, and learn as you build.