Challenge: Eliminating sales bottlenecks
The client came to me with an existing website that was holding the business back: it took up to six seconds to load, had flaws in the purchasing journey (such as a non-intuitive shopping cart), and featured a chaotic list of services. Instead of trying to optimize a site built on a heavy template, I proposed developing a new system from scratch using modern technology to ensure lightning-fast performance.
Service data redundancy problem
Największym wyzwaniem była optymalizacja oferty. Usługi różniły się głównie liczbą jednostek treningowych, co tworzyło nieczytelny gąszcz.
New user flow
Proces zacząłem od rozpisania ścieżki użytkownika (User Journey). Musiałem stworzyć balans: z jednej strony strona musi sprzedawać, z drugiej – budować autorytet trenera.
Visual style
I combined "medical" precision (nutritional expertise, professionalism) with modern, lifestyle-oriented sports. The website wasn't meant to be flashy, but rather to inspire trust.
Iterations
The project was developed in consultation with the trainer at every stage—from wireframes to the selection of photos—to ensure the website’s look and feel perfectly aligned with his brand. Below are a few sections showcasing the established style
Technology, data security, and performance
I built the site using Next.js and Sanity, achieving near-perfect PageSpeed Insights scores. However, the most significant technical challenge was integrating the payment gateway and ensuring the protection of sensitive data (GDPR compliance).
Optimizing service variant management
When building the service configurator, I deliberately opted for a flat data structure rather than complex nested logic. Although this requires assigning a separate price to each of the 16 variants (locations × packages), I chose this model to ensure system predictability and the security of payment data. For a personal training business, a "flat" system is resilient against logic errors, gives the owner full control over pricing via the Sanity dashboard, and eliminates the risk of unexpected price changes—making it a safer and more maintainable solution than even the most sophisticated code.
Scalability
I designed the architecture with the future in mind—the system allows for the addition of further variants (e.g., trainers) at any time as the company grows.
Encryption of sensitive data
To view order data, the trainer must call a dedicated decryption function via the API (triggered by a button). This ensures that customer information remains secure, even in the event of a database leak.
Business independence
I developed a system that allows the trainer (or their SEO specialist) to change prices and add new service packages or categories at any time, without requiring a programmer's intervention. This gives the client complete independence in managing their service offerings.
