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Home Case Study Health & Fitness FitReserve


Multi-feature fitness subscription application

The Tech Stack:





Health & Fitness


Web, iOS, android




8 months

About the project

FitReserve emerged as a health & fitness studio startup with a focus on providing flexibility and convenience of curated workouts. Looking to replace the resigning Chief Technical Officer, the company settled on our DEV team.

Major upgrades and prompt development of the new features enhanced the value of the product, creating opportunities for a successful sale of the app.

After FitReserve had been acquired by the large holding company, the startup extended its distribution to nearly 5 mln of the holding’s employees. At present, the company offers its fitness subscription services across the USA. By choosing from thousands of classes, users can mix the selection of sports studios and instructors.

Among other solutions, the project provides the following:

Variety of training activities to choose from;

Live stream fitness classes;

Personalized instructions;

On-demand workouts from professional sports studios;

Membership subscription with access to different studios available with FitReserve.

Challenges to overcome

Poor technical documentation
The technical documentation was lacking, including information about the infrastructure and automated tests. The way the product works was essentially described via the face to face communication rather than technical documentation. We were yet to find out where the product stands exactly and what it takes to upgrade it.

Unsustainable product
It wasn’t clear how to upgrade the product without damaging its working features. This uncertainty prevented developers from adding new functions.

Tangled source code
The product was written in several languages: Ruby on Rails, ReactJS, and AngularJS. The use of React and Angular languages implies maintaining two separate libraries. In general, the code was difficult to maintain.

Member_Coach-list-1 (1)

The client recommends our service on

The work delivered by JetRuby Agency met all expectations. They were communicative throughout the project and offered excellent suggestions for improvement. Their expertise in this field stood out the most, which helped speed up the processes and develop complex code.

Megan Smyth,
co-founder and CEO

More screens interfaces

Our work

AI and ML solutions

Preliminary technical audit
We started with the description of all product-related processes. It was crucial to start releasing new features without the fear of damaging existing functionality. During one week, we came up with an action plan for the safe release of new features. By the end of the first month, our team gained full clarity regarding the product map and its structure.

AI and ML solutions development

The evolution of the product urged its transformation and thus demanded new extensive functionality. However, at some point, adding new features became complicated or even impossible due to the low stability of the product.

Within 2 - 3 weeks, our efforts were dedicated to writing autotests and technical documentation, as well as refactoring some elements in the source code.

At this stage, our team has ensured the test coverage of the product’s critical business logic. Therefore, we were able to map out its sustainable development.

FitReserve work app

Development of the product
Starting the third week, we focused on increasing the value of the product by adding new useful features and overall stabilization of the app’s functionality. The following functions were introduced:

- Integration with new fitness studios and 3rd-party service providers.
- New membership subscription options for users to let them choose classes in curated gyms and sports studios.
- Activation of 3 new areas, enabling new subscribers from those locations to join the network.
- The web platform was our first priority. Later on, our team joined mobile development.

One of our priorities was to fix the source code and put programming languages in order Since the inherited source code wasn’t easy to maintain, we have to figure it out and make it structured. We tracked down the previous maintainer every week and got a walkthrough of technical aspects.

Our team unified the use of programming languages and found that having two separate code libraries is unnecessary. Gradually, we walked away from the Angular language, which helped us to organize the product’s ecosystem.

Preparing the product for sale

FitReserve achieved a new milestone and it was finally decided on selling the startup business. JetRuby was invited to facilitate the sales as a technical advisor. Our specialists joined tech meetups to walk buyers through the product and its technical framework. We answered the questions on both technical and organizational matters.

Business results

  • During the 8 months of our contribution as maintainers, developers, and CTO, the project matured into a stable application. 
  • JetRuby’s technical guidance provided for a successful acquisition of the startup. Now fitness subscription services benefit 5 million fitness lovers across the USA.
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