TL;DR: The thing that finally pushed me over the edge was discovering that my CGM app stores readings in a proprietary format, exports as a PDF (a PDF ), and wants $12/month to show me a 90-day trend line. That's data my body generated. 📖 Reading time: ~35 min What's in this article Why I Built This Instead of Using an App What You'll Actually Build Project Setup: From Zero to Running Dev Server The Quick-Entry Form: This Is What You'll Use 4x a Day Building the Trend Chart with Recharts Stats Panel: The Numbers That Actually Matter Deploying to Firebase Hosting: 5 Minutes Flat Rough Edges I Hit (And How I Fixed Them) Why I Built This Instead of Using an App The thing that finally pushed me over the edge was discovering that my CGM app stores readings in a proprietary format, exports as a PDF (a PDF ), and wants $12/month to show me a 90-day trend line. That's data my body generated. I should be able to query it however I want without paying a subscription to see a line chart.…