How to Build a Solana Copy Trading Bot That Actually Works

Copy trading on Solana is one of the most requested features in crypto trading bots. Here's how I implemented it in @solscanitbot and the architectural decisions behind it. The Problem You want to automatically mirror another wallet's trades. When they buy a token, you buy it. When they sell, you sell. Simple concept, surprisingly tricky to implement. Two Approaches 1. WebSocket Monitoring (Complex) Subscribe to account changes via Helius WebSocket Parse transaction logs in real-time High complexity, many edge cases 2. Snapshot-Diff (Simple, What I Use) Take snapshot of target wallet's token holdings Wait 60 seconds Take new snapshot Diff the two: new tokens = buys, missing tokens = sells I chose snapshot-diff. Here's why: Why Snapshot-Diff Wins Simpler code — ~50 lines vs 200+ for WebSocket More reliable — WebSocket connections drop; polling always works Easier to debug — you can log each snapshot 60-second latency is fine — for copy trading, seconds don't matter Implementation async