$150K/yearSep 24, 2025

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

Christian KonnerthWishlists

Side ProjectMobile AppPatience
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The Story

Chris turned a simple wishlist app into a $150K/year business without a team, without funding, and with zero marketing. As he puts it: "I turned a really simple wishlist app into a 150K a year business and now 2 months ago I quit my job."

Wishlists is a mobile app that lets users create and share wishlists for Christmas, birthdays, and other occasions. The idea came from a simple observation: "I was still using an Excel sheet for my own wish list because I thought there was no nice and pretty wish list app out there."

The journey started with rejection. In 2019, Chris applied for an app developer job at a bike company he admired. They declined, but said they liked his enthusiasm. "That just gave me the boost. That's when I decided to get into app development because I wanted to have these kind of jobs."

Instead of building yet another to-do list app (there are 2 million of them), Chris built something similar but different - a wishlist app. Six years later, it's a $150K/year business that let him quit his full-time job.

Key Insights

The 6-Year Marathon

  • 2019: Started building in university after job rejection
  • 2020: Released first version of the app
  • 2021: Got first job as app developer (because of the app he built)
  • 2023: Relaunched Wishlists 2.0, hit 100K registered users
  • 2024: Full-time job + side project simultaneously
  • 2025: Quit job, went full-time on Wishlists

As Chris reflects: "Nowadays, everyone would just vibe coded on a weekend, but for me, it took 6 years. So, for me, it was a marathon and not just a vibe coding weekend."

Building Alongside a 9-5

  • Morning (8-9am): Small tasks - support emails, analytics
  • Day (9am-6pm): Full-time job
  • Evening (6-8pm): Personal time, sports
  • Night (8-11pm): Development work
  • 2025: Negotiated 4-day work week for extra dev time

"In the summer I couldn't really motivate myself to keep developing after a full day of developing, so the start of 2025 I negotiated to have a 4 day week to have another full day for Wishlists."

The Zero Marketing Approach

"Being a developer also means that I'm naturally bad at marketing. So, I just didn't do any marketing the standard way. Also, I simply didn't have the money for it."

Instead, Chris focused on:

  • Friends and family reviews - "I just asked everyone I know for reviews. That was super awkward at first, but that's what has helped me a lot."
  • Strategic review timing - "I'm just showing it after the user has accomplished something. For example, has added a wish or fulfilled a wish. So when the user feels good."
  • Personal support emails - "Every time I shipped a feature or just fixed a bug for someone specific user, I would text these users, 'Hi John, I just fixed your issue.'"

4-Step Side Project Playbook

Step 1: Start small with an actual problem

  • "I guarantee you if you have this problem there's at least one more person on this earth with the same problem and that should be enough to start this project."

Step 2: Set correct goals

  • "If I had set my goal 6 years ago to have 150K a year, I would have thrown away that project. So my first goal was not to get the million dollars but to have a random person who I don't know download the app."
  • "Users first, monetization later."

Step 3: Be honest with your employer

  • "Be upfront about your side project because that's mutual beneficial. You learn so much at your work... But having a side project means you have to do everything and that's also super beneficial for your work."
  • "Use every free time you get. Car rides, train rides."

Step 4: Use winter wisely

  • "In winter, no one's going to say, 'Oh, look how nice the weather is outside. How can you be inside coding?' That will not happen in winter."
  • "I really started to like working holidays because that just combines being social and being productive. Find a small group of friends or colleagues... It just helps a lot being around other motivated people."

Business Numbers

  • $150K/year (~$6K/month in low season, 5x in high season)
  • 1.1 million registered users
  • 4,000+ paying customers
  • 110K monthly active users
  • 99% profit margins ("I don't really have the costs beside my server costs")

Revenue Model

  • In-app purchases: Premium features like custom wishlist images
  • Affiliate links: Amazon links converted to affiliate links ("Once I open this link from within Wishlists, I get money because I'm changing it to an affiliate link")

Tech Stack

  • Flutter (cross-platform)
  • Firebase (backend, analytics)
  • Cursor IDE
  • ChatGPT
  • RevenueCat (in-app purchases)
  • Thrill (user feedback)
  • OneLink (deep links)
  • SelfDesk (accounting)

Key Advice

"Do not over complicate things. Not everyone has to fly to Mars. You don't have to build the next Facebook. You don't need VC funding. Find a problem you can solve by yourself. Find an actual problem you or someone else has and just give it a try. Even if that just means making a prettier version of an existing app."

Resources