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

Sebastian

• Background and Origin Story
  • Studied computer science in Germany for roughly six years and completed a master’s thesis.
  • Worked for three years as a programmer at a mid-sized German company.
  • Became restless after staying on the same corporate project and wanted more creative control over his own work.
  • Quit his job with 12 months of runway to focus on indie app development.
  • Returned to his old job after the 12-month deadline because the business had revenue but was not yet large enough to support him full time.
  • Quit his job a second time at the start of 2024 after the business became strong enough to give him full control over his time.
• Pivotal Moments and Turning Points
  • Spent the first six months struggling with low revenue and limited traction.
  • Felt both like a failure and a success because the business was not yet big, but it had reached meaningful side-project revenue.
  • Reached $3,000 in monthly recurring revenue by the end of 2023.
  • Grew Habit Kit to more than $15,000 in monthly recurring revenue by the end of 2024.

Products and Offerings

• Habit Kit
  • Built Habit Kit as a visually appealing, simple habit tracking mobile app.
  • Helped users build and maintain daily habits.
  • Focused the first version on a tile-based grid chart for habits and a clean, simple interface.
  • Included basic habit tracking and progress visualization in the MVP.
  • Stored all data locally on the user’s device.
  • Required no sign-in or authentication, giving users full control over their data.
• Other Apps and Experiments
  • Built multiple apps for the App Store before Habit Kit.
  • Saw some earlier apps flop while others generated smaller side-project revenue.

Metrics and Financials

• Growth Metrics
  • Reached roughly 300,000 combined downloads across the App Store and Google Play.
  • Collected more than 2,000 reviews and ratings.
  • Ranked for several important keywords in the habit tracking category.
  • Ranked in the top five for the keyword “habit tracker” in multiple countries.
• Revenue
  • Built Habit Kit to $15,000 in monthly recurring revenue.
  • Considered $1,000 in revenue from a side business to be a meaningful success.
  • Reached $3,000 in monthly recurring revenue by the end of 2023.
  • Reached more than $15,000 in monthly recurring revenue by the end of 2024.
• Costs
  • Ran the business as a solo developer with no employees.
  • Paid RevenueCat as the largest expense because it takes 1% of revenue.
  • Kept remaining monthly expenses around $200 to $300.

Strategy and Growth

• Building in Public
  • Shared the development journey across X, LinkedIn, Blue Sky, and Threads.
  • Posted authentic updates about wins, failures, and progress.
  • Created opportunities to appear on podcasts, get featured in videos, and connect with other app developers.
  • Posted early screenshots and used the positive response as a signal to launch quickly.
• App Store Optimization
  • Treated app store optimization as the biggest growth lever.
  • Edited app metadata such as keywords, app name, subtitle, and screenshots to improve rankings.
  • Focused on the keyword “habit tracker” and placed it at the start of the app name.
  • Asked users for reviews immediately after they checked off their first habit.
  • Used that first success moment to collect more five-star ratings and reviews.
• Apple Search Ads
  • Ran a simple, low-budget Apple Search Ads campaign.
  • Spent about $100 per month.
  • Used the campaign as a potential ranking boost strategy because he hoped Apple favored developers who advertised on the platform.
• Idea Selection and Validation
  • Recommended starting by building anything because more ideas emerge once the builder gets into motion.
  • Built apps that solved his own problems.
  • Used himself as the first customer so he could understand the requirements and what worked.

Tech Stack and Infrastructure

• Development
  • Built Habit Kit with Flutter.
  • Used Flutter to deploy to iOS and Android from a single codebase.
  • Built the first version in about two months.
  • Used Cursor as an AI-powered IDE for autocomplete and problem-solving conversations.
• Analytics, ASO, and Monetization
  • Used Astro for keyword research and app store optimization.
  • Used App Figures for app analytics, marketing, and some keyword research.
  • Used RevenueCat to handle subscriptions and purchases.
• Personal Tools
  • Used Habit Kit for his own habit tracking.
  • Used Waycast, ChatGPT, and 1Password as important tools in his workflow.

Lessons and Advice

• Competing on App Stores
  • Learned that a solo developer can compete against bigger companies and long-standing app store competitors.
  • Found that strong keyword rankings can drive meaningful organic traffic.
  • Believed a strong app store ranking can reduce the need for a large marketing budget.
• Advice to Other Founders
  • Suggested saving enough money for a sabbatical to focus on building an app business.
  • Said quitting his job gave him the focus he needed because he could not find motivation to code on his own apps after a full day of programming.
  • Treated the 12-month deadline as the foundation that helped him start building his dream business.