Claude Writes the Code, Gemini Runs It: How Two Competing AIs Cut My SaaS Costs by 30x

Claude Writes the Code, Gemini Runs It: How Two Competing AIs Cut My SaaS Costs by 30x I build Nokos, an AI-powered note-taking app that auto-captures conversations from 25+ AI tools. Here's the thing — the product itself runs entirely on AI, and picking the wrong model for the wrong job almost killed the economics. This is the story of how I went from "this will never be profitable" to "break-even at 150 users" by splitting my AI stack between two competing providers. The Original Architecture (And Why It Was Bleeding Money) When I first built Nokos, I used Anthropic's Claude for everything: Feature Model Cost per call Metadata generation Claude Haiku ~¥0.5 AI Chat Claude Sonnet ~¥4.5 Personal AI (RAG) Claude Sonnet ~¥4.5 Daily Diary generation Claude Haiku ~¥1.5 Session summary Claude Haiku ~¥1.0 Natural Language Search Claude Haiku ~¥0.5 The per-user costs added up fast. With the Plus plan priced at ¥480/month, I was losing money on every paying user. The math was simple: this produ