GitHub Copilot vs Cursor vs Claude API: Which AI Coding Assistant Dominates in 2026? I tested all three for 30 days across real production code. Here's what actually matters for serious developers. The Setup Three tools. One month. One ambitious goal: build a real SaaS feature from scratch using each one as my primary copilot. The Test: Language: TypeScript + React Project: Real-time data dashboard with WebSocket sync Metrics: Time to feature complete, bug density, code quality, learning curve The Contenders: GitHub Copilot ($20/mo or included in Copilot Pro) Cursor ($20/mo Pro or free with limitations) Claude API (Claude 3.5 Sonnet @ $0.003/$0.015 per 1K tokens) Performance Comparison Speed to First Working Feature Winner: Cursor — 3.5 hours from blank file to deployed feature. Cursor's "Cmd+K" inline editing is borderline magical. You describe what you want, it rewrites the exact lines you need without touching the rest of your file. Copilot makes you accept or reject entire chunks.…