Your stack is just the set of tools you'll use to build your product. Every tool costs money, takes time to learn, and locks you in a little.
Your stack is the set of tools your product runs on. Every tool you pick does one job: database, authentication, payments, hosting, AI, voice. You're not building these things. You're renting them.
RESTAURANT: Your stack is your kitchen equipment. You don't forge your own knives or build your own oven. You buy the best you can afford, learn how they work, and focus on the food. The food is your product. The kitchen is your stack.
The goal is simple: rent the boring stuff so you can focus on the stuff that makes your product special. Nobody switched to your product because you wrote your own authentication system. They switched because your product does something theirs doesn't.
Every tool you evaluate comes down to four questions:
1. Does it work right now? Not "coming soon." Not "in beta." Does it work today, in production, with real users? If the answer is no, move on.
2. Can one person operate it? Some tools are powerful but require a dedicated engineer to maintain. If you need to hire someone just to keep the tool running, it's the wrong tool for a solo founder.
3. What does it actually cost? Not the enterprise tier. Not the "contact sales" plan. What does it cost at your scale — 100 users, 1,000 users, 10,000 users?
4. How locked in are you? Can you export your data? Can you switch to a competitor in a weekend, or would it take six months? The cheaper the switching cost, the better.
DEF: Lock-in — When a tool makes it expensive or difficult to leave. Your data is in their format, your code depends on their SDK, and migrating would take weeks. Some lock-in is acceptable. Total lock-in is dangerous.
Here's every tool that runs Project Fluency, what it does, what it costs, and what restaurant role it fills:
React Native + Expo — The kitchen itself. One codebase, two platforms (iOS and Android). Expo handles the build system so you never touch Xcode or Android Studio directly.
COST: Expo free tier covers most solo founders. EAS Build at $15/month when you need faster builds. React Native is free and open source.
Supabase — The walk-in cooler. Your database, authentication, file storage, and serverless functions all in one place. PostgreSQL under the hood, which means you're not locked into proprietary query language.
COST: Free tier for development. Pro plan at $25/month covers most early-stage products. Scales predictably — no surprise bills.
ElevenLabs — The voice of your characters. Text-to-speech, speech-to-text, and conversational AI. The quality gap between ElevenLabs and competitors is not small — it's the difference between a real conversation and talking to Siri.
COST: Starter at $5/month for development. Scale plan at $99/month for production. This is your biggest variable cost and the one you need to watch closest.
Claude API (Anthropic) — The head chef's brain. Content generation, assessment scoring, conversation memory, structured data extraction. Sonnet for complex production tasks. Haiku for batch processing and summarization.
COST: Pay per token. Roughly $3-8/month at early scale. Scales with usage but the per-unit cost is predictable.
Webflow — The front of house. Your marketing website, pricing page, character profiles, landing pages. No-code with enough flexibility to embed custom JavaScript when you need it.
COST: CMS plan at $29/month. Handles everything a solo founder needs for web presence.
Stripe — The cash register. Payments, subscriptions, invoicing. The integration is straightforward and the documentation is the best in the industry.
COST: 2.9% + $0.30 per transaction. No monthly fee. You only pay when you make money.
Firebase — Google's all-in-one backend. Powerful but the pricing model is unpredictable at scale. One viral moment could bankrupt you. Supabase gives you the same features with PostgreSQL and predictable billing.
Vercel — Great for Next.js web apps but overkill when your primary product is a mobile app. Added complexity without proportional benefit.
Flutter — Google's mobile framework. The Dart language is a barrier — harder to find AI coding assistance compared to JavaScript/TypeScript. React Native's ecosystem is larger and AI tools understand it better.
NOTE: The best stack is the one you can operate alone at 2 AM when something breaks. Evaluate tools by their worst-case scenario, not their best-case demo.