I vibe-coded a free German learning app — here's what I actually ended up with

I've been building LinguStream on and off for way too long, and it started as a simple question: why does the best German learning method (LingQ-style immersion) cost money? The idea is straightforward — you read real German texts, click words you don't know, save them, and review with spaced repetition. No artificial exercises, just real content and vocabulary in context. What I used: React 19, TypeScript, Vite, Supabase (auth + database + edge functions), shadcn/ui, Tailwind, and DeepSeek for AI features — all proxied through Supabase edge functions to keep keys off the client. For the vibe coding itself, I leaned heavily on Claude Sonnet and Opus from Anthropic — honestly couldn't have got this far without it. What it does: Import any German text, article, or podcast transcript Click unknown words to save them instantly Spaced repetition review (SM-2 algorithm) 10 quiz types Completely free I'm at the point where I genuinely can't tell if it's actually good anymore — I've been stari