How I Built It: $15K/month Mobile App

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url	How I Built It: $15K/month Mobile App Sebastian Ro quit his corporate coding job and leveraged a combination of "Building in Public" and targeted App Store Optimization (ASO) to scale Habit Kit—a visually clean, local-first habit track... https://www.youtube.com/watch?v=gpn1jEoWT4A

TL;DR

Sebastian Ro quit his corporate coding job and leveraged a combination of “Building in Public” and targeted App Store Optimization (ASO) to scale Habit Kit—a visually clean, local-first habit tracking mobile app—to 300,000 downloads and $15,000 MRR.

The Founder’s Story

Sebastian Ro studied computer science in Germany for six years before taking a regular programming job at a medium-sized company. After three years of working on the same corporate project, he became restless and craved a creative outlet to build his own software.

He decided to save money for a sabbatical and quit his job, giving himself a hard 12-month runway to build something profitable. The first six months were incredibly challenging, generating minimal revenue. When his 12-month deadline expired, Sebastian actually returned to his old programming job, running his app business as a side hustle.

By the end of 2023, the side project reached $3,000 MRR, and by late 2024, it exploded to over $15,000 MRR, allowing Sebastian to quit his day job for a second—and final—time.

The Building Process

Sebastian conceived the idea for Habit Kit in the summer of 2022 to solve his own need for a clean, visually appealing habit tracker. He selected Flutter as his development framework, enabling him to build and deploy to both iOS and Android with a single codebase.

Sebastian’s design prioritized a minimal, tile-based grid chart (similar to GitHub’s contribution grid) to visually represent habit progress. Crucially, the app was designed local-first: all user data is stored strictly on the device, requiring no authentication, sign-in, or database sync. This respect for privacy became a powerful selling point.

Sharing early screenshots of the UI on social media generated immediate positive feedback, driving Sebastian to code aggressively and ship the MVP in just two months.

Launch & Marketing Strategy

Aggressive Building in Public: Sebastian shared his development journey, featuring visual updates, UI iterations, and authentic reports of his wins and failures across X, LinkedIn, Blue Sky, and Threads. This active sharing built an organic audience and unlocked unexpected growth channels, leading to podcast invites, video features, and deep connections with other prominent developers.
ASO Keyword Placement: Sebastian mapped his meta keywords using dedicated tools. He focused on the hyper-competitive term “habit tracker” and placed it at the absolute beginning of his app’s name (e.g. Habit Kit - Habit Tracker) to secure a top 5 ranking in multiple countries.
Micro-Success Review Prompts: To build high-tier domain authority on the App Store, Sebastian implemented a clever rating funnel: he displays the native iOS/Android review dialog immediately after a user completes their very first habit check-off. Because they are experiencing a micro-moment of personal success, they are highly likely to give a positive response, resulting in 2,000+ five-star ratings.
Ad Arbitrage Experiments: Sebastian runs a tiny, low-budget Apple Search Ads campaign, spending just $100 per month. He uses this as a strategic keyword ranking booster, hypothesizing that Apple’s App Store algorithm subtly favors developers who buy advertising space on the platform.

Tech Stack

App Framework: Flutter
IDE & AI Coding: Cursor (utilizing auto-completions and interactive chat to troubleshoot styling and framework issues)
Subscription Management: RevenueCat (representing his largest expense, taking a 1% cut of revenue)
ASO & Keyword Tools: Astro (for keyword research, search popularity, and difficulty checks) and Appfigures (for analytics)
Productivity Tools: Raycast, 1Password

Key Quotes & Metrics

Monthly Recurring Revenue (MRR): $15,000
Total Downloads: ~300,000 (across iOS and Google Play)
Reviews & Ratings: 2,000+
Monthly Operating Costs: ~$200–$300/month (excluding RevenueCat’s 1% fee)
“Save money for Sabbatical to focus on development of your app… I couldn’t find motivation to code on my own apps after I programmed for 8 hours on my regular job.”
“If you manage to secure a good ranking on the app store, you don’t need a big marketing budget and you can compete with bigger brands.”

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