This app replaced my 9-5 ($150K/year)

SUMMARY

Christian Konnerth shares how he built the Wishlists app—a simple wishlist-sharing tool—into a $150K/year business as a side project alongside his 9-5 job, eventually quitting two months ago to go full-time.

STATEMENTS

Christian Konnerth developed the Wishlists app over six years, starting in university and continuing through a full-time job as an app developer.
He began the project after rejection from a dream job motivated him to learn app development, leading to his first professional role.
The app serves as a user-friendly alternative to spreadsheets for managing and sharing personal wishlists, especially for holidays like Christmas.
Konnerth maintained a disciplined schedule: one hour on non-development tasks in the morning, full-time work from 9 to 6, personal time until 8, and development from 8 to 11 in the evenings.
He negotiated a four-day workweek in early 2025 to dedicate more time to the side project without quitting immediately.
Key learnings include being transparent with employers about side projects, prioritizing relationships, and leveraging winter months for focused work.
Growth relied on organic methods like user reviews from friends and family, in-app prompts at positive moments, and personalized support responses.
The app reached 1.1 million registered users, 110K monthly active users, and $6K average monthly revenue, scaling fivefold in high season.
Monetization comes from in-app purchases for premium features and affiliate links for product imports from sites like Amazon.
Konnerth advises starting small with real problems, focusing on users before monetization, and enjoying the process as a low-risk side endeavor.

IDEAS

Rejection from a desired job can spark self-motivation to acquire new skills, turning setbacks into career-launching opportunities.
Everyday frustrations, like managing wishlists via spreadsheets, reveal untapped app ideas that solve personal problems scalable to others.
Balancing a side project with a full-time job requires micro-habits, like using commute time for non-coding tasks to build momentum.
Transparency about side hustles with employers fosters mutual benefits, applying job-learned skills to personal ventures.
Winter seasons offer guilt-free productivity windows for coding, contrasting summer's distractions from outdoor activities.
Working holidays with like-minded peers blend social interaction and motivation, safeguarding mental health during intense building phases.
Initial goals for side projects should be modest, like gaining one unknown user, to avoid overwhelm and sustain long-term effort.
Prioritizing user delight through timely support and feature implementation drives organic sharing and positive reviews without traditional marketing.
Personalized follow-ups with users, turning feedback into tailored fixes, build loyalty and turn supporters into reviewers.
Simple apps can achieve high margins (99%) by minimizing costs, focusing on core functionality like affiliate integrations over complex features.
Launching imperfect versions early allows iterative improvements, as seen in relaunching Wishlists 2.0 after codebase issues.
Side projects demand a marathon mindset, with realistic timelines spanning years rather than weekend sprints for sustainable growth.

INSIGHTS

Personal pain points, when addressed through minimal viable products, can evolve into profitable businesses by tapping into shared user needs without initial monetization pressure.
Structured time management, integrating side work into daily routines and seasonal advantages, enables solopreneurs to scale projects alongside full-time commitments.
Organic growth through relationship-building and user-centric support outperforms budgeted marketing, fostering authentic community and retention.
Modest, achievable milestones prevent burnout in long-term pursuits, transforming side hobbies into viable careers over extended periods.
High-margin digital products thrive on simplicity, leveraging existing ecosystems like affiliates to generate revenue with low overhead.
Surrounding oneself with motivated networks during key phases sustains productivity and emotional resilience in solo endeavors.

QUOTES

"I turned a really simple wish list app into a 150k a year business without a team, without funding, with zero marketing."
"Rejection is the ultimate motivation."
"Start small. I start with an actual problem either you or someone else experienced because I guarantee you if you have this problem there's at least one more person on this earth with the same problem."
"Do not over complicate things. Not everyone has to fly to Mars. You don't have to build the next Facebook."
"It's a marathon and not just a vip coding weekend."

HABITS

Wake up at 8:00 AM and dedicate the first hour to light side project tasks like checking analytics or responding to emails.
Use commute times, such as car or train rides, for productive non-development activities to maximize free moments.
Prioritize evenings from 8:00 to 11:00 PM for focused coding after personal time and exercise, adjusting for seasonal energy levels.
Negotiate flexible work arrangements, like a four-day week, to carve out dedicated full days for the project.
Engage in working holidays with motivated peers to combine productivity, social interaction, and mental health maintenance.

FACTS

Wishlists app has 1.1 million registered users and 110,000 monthly active users, multiplying by five during peak holiday seasons.
The app generates an average of $6,000 in monthly revenue during low seasons, primarily through in-app purchases and affiliate links.
Konnerth built the app using Flutter for cross-platform development, Firebase for backend and analytics, and tools like ChatGPT for assistance.
He reached 100,000 registered users by the end of October 2023, coinciding with the launch of Wishlists 2.0 after university graduation.
The business operates at 99% margins due to minimal costs beyond server expenses, with around 4,000 paying customers.

REFERENCES

Flutter (cross-platform development framework).
Firebase (backend, analytics).
ChatGPT (AI assistance tool); Starter Story Build (AI-powered app-building program).

HOW TO APPLY

Identify a personal problem, like disorganized wishlists, and validate it by confirming others share the issue before investing time.
Set modest initial goals, such as acquiring one unrelated user, to maintain motivation without the pressure of grand financial targets.
Structure your day around your full-time job: allocate mornings for quick admin tasks, evenings for core development, and leverage commutes for planning.
Build transparency by informing your employer about the side project early, highlighting how it enhances your professional skills and benefits the team.
Focus on user feedback from day one by implementing a simple support system, personally addressing requests to foster loyalty and organic growth.

ONE-SENTENCE TAKEAWAY

Simple side projects solving real problems can evolve into full-time freedom through consistent, user-focused effort over years.

RECOMMENDATIONS

Solve everyday annoyances you or others face with minimal apps, prioritizing launch speed over perfection.
Integrate side work into existing routines using seasonal advantages like winter for deeper focus sessions.
Cultivate organic growth by personally engaging users via support, turning feedback into features and reviews.
Delay monetization until user base solidifies, then layer in simple revenue like affiliates for high margins.
Surround yourself with motivated networks through working holidays to balance productivity and well-being.

MEMO

In an era where side hustles promise escape from the grind, Christian Konnerth's journey with Wishlists stands as a quiet testament to persistence. What began as a university student's frustration with clunky Excel sheets for holiday gift ideas evolved into a sleek app that now generates $150,000 annually. Konnerth, a soft-spoken developer from Germany, built this digital wishlist-sharing tool over six years—three in school, the rest juggling a full-time coding job—without a dime of funding or a marketing budget. Two months ago, he finally traded his 9-to-5 for full-time entrepreneurship, proving that simplicity can outpace spectacle.

The spark ignited in 2019, when rejection from a dream gig at a trendy bike startup fueled Konnerth's self-taught dive into app development. "Rejection is the ultimate motivation," he recalls, opting for a wishlist app over the saturated to-do list market. Users create shareable lists for occasions like Christmas, importing items from Amazon via affiliate links that quietly drive revenue. In-app upgrades, such as custom images, add premium appeal. Yet Konnerth's secret wasn't flashy tech; it was discipline. Mornings started at 8 a.m. with an hour of emails and analytics, evenings stretched to 11 p.m. for coding after workouts and family time. Summers tested his resolve, but winters became sacred coding seasons, free from sunny distractions.

Balancing acts defined his path. Negotiating a four-day workweek in 2025 gave Wishlists breathing room, while transparency with his employer turned potential conflict into synergy—lessons from the job sharpened his solo venture. Growth trickled in organically: early reviews from awkward asks to friends and family boosted App Store rankings. In-app prompts timed for user highs, like adding a wish, elicited glowing feedback. Konnerth's inbox became a goldmine; he'd fix bugs or add features per user requests, then circle back with a simple query: "Do you like it?" This personal touch built a loyal base of 1.1 million registered users, 110,000 monthly actives, and $6,000 in low-season revenue—scaling fivefold during holidays.

Behind the scenes, Wishlists runs lean on Flutter for cross-platform ease, Firebase for backend muscle, and ChatGPT for efficiency. At 99% margins, costs barely dent the till beyond servers. Konnerth's timeline—a 2020 launch, 2023 relaunch post-university, full-time pivot in 2025—defies the weekend-hustle myth. "It's a marathon, not a sprint," he says, echoing tales of slow-burn successes. For aspiring builders tethered to day jobs, his playbook urges starting small: tackle a real problem, chase one stranger's download, savor the fun before profits.

Ultimately, Konnerth's story demystifies the solopreneur dream. No VC pitches, no viral campaigns—just iterative grit and user empathy. In a world chasing unicorns, Wishlists reminds us that a prettier notes app can rewrite your life, one shared wish at a time. As he advises, "Do not overcomplicate things." For those eyeing their own escape, the message is clear: begin where you stand, persist through the seasons, and let simplicity lead the way.