I Built a Julius AI Alternative in Next.js — Here's What I Learned

Auth: Firebase Authentication Database: Fire AI: Google Gemini Flash (switched from GPT-4 - on this) Hosting: Vercel (frontend) + Render (backend API) Payments: LemonSqueezy (coming soon) Total monthly cost at zero users: ~$0. At 100 active free users: still roughly $0. The free tiers on all of these are genuinely generous. The AI cost problem - and how I solved it This is the thing that almost killed the project before it started. My first implementation was naive: user uploads CSV → I send the entire file to the AI → AI answers the question.