How one bootstrapped founder built a $100K/month Android app

Executive overview

Most founders default to iOS, but Android is underserved and significantly cheaper to advertise on. Steve built Joinable, an AI calorie counter, to nearly $1M ARR — with 80% of revenue from Android.

iOS CPMs run four times higher than Android, yet iOS users convert only ~20% better. For a bootstrapped team, that math points firmly to Android.

The compounding advantage of Android: lower acquisition cost, less competition, and Google's full ad network working as one channel.

Why Android over iOS

• iOS CPMs are ~4x higher than Android; conversion rates differ by only ~20%
• Five times as many iOS apps released in recent years vs. twice as many Android — saturation is on iOS
• Android campaigns on Google generate spillover installs on iOS at no extra cost
• Google App Campaigns reach Search, Play Store, YouTube, Display, and Discover from a single campaign

The six-step Google Ads playbook

1. Set up attribution and measurement — send install, paywall, trial, and purchase events (with value) to Google Ads so the algorithm can optimise
2. Launch install campaigns — feed the algorithm baseline data; start at $10–$15/day; use stock images if needed, flood with assets
3. Asset optimisation phase — test big creative swings (not minor tweaks); update Play Store screenshots, title, and description — these are used directly in App Campaigns
4. Launch a Target CPA campaign — once assets are proven and you have consistent purchase data
5. Budget rule: 10x your CPA — if a free trial costs $15, you need $150/day minimum for Google to hit 10 target events and optimise
6. Scale and convert — raise budgets incrementally; continuously improve paywall and pricing to lift subscription conversion rate; flywheel repeats

Where the Android opportunity is

• Successful iOS apps with no Android equivalent are direct targets
• Niche problems that incumbents ignore — lower dev costs now make small audiences viable
• International markets (localisation) open large, underpenetrated user bases
• Follow the data from your own campaigns, not conventional wisdom from social media

Tech stack and operating costs

• Backend: Firebase, GA4, BigQuery, GCP, Google Play
• Subscriptions: RevenueCat (~30K active subscribers managed)
• AI: OpenAI API
• Tools: Claude Code ($100/mo), GitHub Copilot ($39/mo), CodeRabbit ($30/mo), Fixer for AI email support ($30/mo), n8n ($24/mo), AppFollow for ASO ($180/mo), Webflow ($18/mo)

Founder advice

• Start documenting your journey publicly from day one — content creation is a compounding asset
• 80% of decisions should be driven by your own product data, not external trends
• Optimise conversion rate continuously; rising conversion unlocks higher ad budgets and accelerates the flywheel