[Update] I Went Full-Time In My API Side Project And Have Tripled To 300K User Downloads

Published: April 17th, 2023
Guillaume Monnet
Founder, Mockoon
from Luxembourg
started September 2017
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Hello again! Remind us who you are and what business you started.

Hi, my name is Guillaume, I am a full-stack developer, and I created Mockoon a bit more than five years ago. Mockoon is a set of developer tools to make API mocking easier. It includes a desktop application, a command line interface, and various libraries and Docker files to facilitate deployments.

For non-developers, API mocking is a technique that imitates an API that doesn’t exist yet, or to which you don’t have access. It can greatly accelerate the development of an application. Our tools are still open source, and I am thinking about monetization mainly through a cloud offering.

Mockoon has been growing steadily for 5 years, totaling more than 300k downloads, and traffic has doubled in the past year.


Tell us about what you’ve been up to. Has the business been growing?

I am proud of Mockoon's sustained growth over the years. When you start working on a project (a side project at first), it’s sometimes hard to stay motivated.

I know I am in this for the long run, but seeing some growth and good user feedback during the years is what kept me motivated.

Since the last interview two years ago, Mockoon’s monthly active users have tripled, and website visits have more than doubled.


The recipe for growth is the following (not very original, I know):

  • Keep building an awesome product by adding more features that people want.
  • Write content.

Being a developer, building the product was the easy part, not always technically, but at least in terms of motivation. What was more difficult was adding requested features while avoiding cluttering the application. There is always an arbitrage between pleasing everybody and keeping the project roadmap coherent. I also have an opinion about what Mockoon should or shouldn't be. But sometimes, user feedback can change my mind.

After a burnout in late 2020, I decided that my best choice was to quit my job and focus full-time on this project.

I still believe that building a good product greatly contributes to its growth through word of mouth and spontaneous content creation by the community, like tutorials, etc.

However, this is not enough.

Two years ago, I acknowledged that writing no content during the first three years was not a good move. So, I started creating content, which, as a developer, was the hard part. Especially finding the motivation to write and showing up every day!

I settled on working half-time on the product and half-time on the content. I usually split my day more or less 50/50 between the two tasks. Anyway, I cannot stay focused on the same topic, technical or not, for more than a few hours.

Since then, I have published dozens of tutorials, articles, landing pages, documentation topics, etc. Every time I learn a lot, what works or not, and what doesn't work, but suddenly brings traffic after nine months of silence (thank you, SEO).

I do not have a secret recipe. Initially, I began writing pieces on topics that appeared to have the most apparent return on investment, such as a tutorial on "Getting Started with Mockoon." Everybody wants that.

Then, I did simple keyword research using the Google Keyword Planner tool. Essentially, I entered the broad topic of my app's relevance, "API mocking," and tried to identify all the various search queries that people were using for which I could quickly write content.

As a result, I wrote various articles such as "React API mock," which has now become one of the main sources of traffic. However, I believe there is still room for improvement and I plan to step up my keyword research game in the near future!

It is now starting to pay off with the stats shown above. Impressions and clicks on Google more than doubled, and it keeps growing.


But SEO is a long-term game, and it's essential to keep the motivation, especially at the beginning when staring at flat curves.

Show up every day and write something, even if it is tiny!

Apart from this, I am not investing much in social networks. I find the ROI between time invested and traffic to be low.

Compared to SEO, where writing an article will bring a continuous flow of visits over the years, writing a Twitter or Reddit post will take some time and only generate a tiny amount of visits during a short time.

There is one exception for me, due to the nature of my user base, and it's LinkedIn. Posting something there usually has a better and longer return.

What have been your biggest challenges in the last year?

After a burnout in late 2020, I decided that my best choice was to quit my job and focus full-time on this project.

Mockoon being pre-revenue, this was a bit scary. But the volume of users convinced me to try something. I also would have hated myself if I had stopped working on the project instead.

Fast forward two years, and I am really happy with my choice, even if this is financially a bit stressful. I still have to work as a freelancer while working on Mockoon. But my work-life balance is better now.

I will focus a bit on building a cloud offering that some users are awaiting. It should bring financial stability and transform this endeavor into a small business from which I can make a living.

What have been your biggest lessons learned in the last year?

The biggest lesson is that I cannot hustle for years. I am trying to build a bootstrapped company which will take years. It has been only two years since I quit my job to focus full-time on Mockoon, so this is just the beginning.

So, releasing the pressure and working less (hello, four days a week!) has been the best choice. I am still as productive as before but way less stressed and happier.

I also stopped seeing everything as an emergency and having FOMO every time I couldn't complete a task during the day.

I learned to accept that if I take care of my kids or do some sport one afternoon, Mockoon will not die.

What’s in the plans for the upcoming year, and the next 5 years?

I have a long list of cool features to add to the tools and lots of ideas for new marketing content. I want to see the project grow and serve more users every month.

The majority of my work involves developing features based on issues opened on GitHub that have been upvoted, as well as taking into account the needs of users and what they are attempting to accomplish.

For example, one of the recent features I added - CRUD endpoints (apologies to the non-technical readers) - wasn't a highly upvoted issue on GitHub. However, it was a major pain point, with users indirectly requesting it at least once a day on our Discord server. As a result, I made it a priority over other more popular requests. It also made a lot of sense to add this to the tool.

In addition, I believe that having a clear product vision is crucial. I may reject highly upvoted features if they do not align with the product vision. However, I am open to changing my mind if users make a compelling case for the inclusion of a specific feature. This has happened in the past since I do not have all the answers!

This year, in parallel, I will focus a bit more on building a cloud offering that some users are awaiting. It will offer optional cloud services like AI-generated API mocks and settings synchronization. It should bring a bit of financial stability and, I hope, transform this endeavor into a small business from which I can make a living. This will not put in question the open-source nature of the project. On the contrary, I think it will serve the project well as I will be able to focus more on it instead of freelancing on the side.

What’s the best thing you read in the last year?


After reading business-related books, blogs, and news, for years, I reduced the time I spent on “work” related things.

I think I had some fatigue from always reading about the same topic, urging me to validate this, analyze that, work on my unique value proposition, etc.

So, I stopped and decided to re-start reading fiction books instead of focusing on the business aspect of everything.

I am cutting the information overload and releasing the pressure.

You should try it!

Advice for other entrepreneurs who might be struggling to grow their businesses?

Try to find the reason why there is no growth. Usually, something is amiss: there is no problem to solve, you are not providing the right solution, and you are not doing any marketing (content writing, etc.).

Of course, this may sound obvious, straight out of a startup book, but it is usually one of these reasons. I saw all these cases in my entourage these last few years.

Be especially wary of self-validating a problem or a solution just because you think it is the right thing to do or because you dealt with the situation in the past. You will not be your customer. Surely you need a vision for your project or product. But as soon as you can validate with metrics or by talking to your users, you should.

Also, know when to quit working on a feature and when to double down or keep working hard. Some things may take time, especially if you bootstrap.

Where can we go to learn more?

  • The official website, where I publish blog articles and tutorials
  • My Twitter where I post development progress from time to time