Chart Image Generator

Generate PNG chart images from data using Vega-Lite. Perfect for headless server environments.

Why This Skill?

Built for Fly.io / VPS / Docker deployments:

• ✅ No native compilation - Uses Sharp with prebuilt binaries (unlike canvas which requires build tools)
• ✅ No Puppeteer/browser - Pure Node.js, no Chrome download, no headless browser overhead
• ✅ Lightweight - ~15MB total dependencies vs 400MB+ for Puppeteer-based solutions
• ✅ Fast cold starts - No browser spinup delay, generates charts in <500ms
• ✅ Works offline - No external API calls (unlike QuickChart.io)

Alternatives and why they don't work well on Fly:

• canvas npm - Requires native compilation, fails on minimal Docker images
• Puppeteer + Chart.js - 400MB+ Chrome download, slow cold starts, memory heavy
• QuickChart API - External dependency, rate limits, privacy concerns
• Plotly - Needs Puppeteer for static image export