Zenfit

Challenge

Zenfit is software for fitness coaches to run their clients' workout and meal plans. When Maksym joined, it already had paying customers and a sales team, but the product had been built fast to get there. The code was fragile, insecure in places and hard to change without breaking something else, while the business was aiming for aggressive growth.

Solution

Working in a team of three developers, Maksym gave the platform its shape while new features kept shipping:

• Closed the security holes first, then moved authentication and data protection to current standards.
• Split the monolith into a single-page frontend on a clean REST API, and refactored legacy modules into documented code.
• Added unit and integration tests, Docker and CI/CD, so releases stopped being a risky event.

Result

The user base grew 3x. Then a Danish competitor acquired Zenfit and the two products had to become one. Each side had features worth keeping, so after first connecting the systems through APIs, Zenfit moved onto the acquirer's Node.js backend: one backend and two frontends serving two customer bases. Four years in total, from fragile code to a successful exit.