I'm doing weightlifting for about 8 months already. I followed Stronglifts 5x5 weightlifting routine, and it was a great program for beginners, and I really liked their app, but it's a newbie program, so I had to switch to something.
A lot of weightlifters recommend 5/3/1 programs as the next step, and I liked the approach there. But I couldn't use the Stronglifts 5x5 app anymore. I tried to find a replacement app, and there're 2 types of them:
Jefit, Strong, etc - they're really pretty and nice, but they have no notion of a program. They won't tell you when to increase the weight, when to decrease it, etc - you'd have to do all of that manually, which is daunting
Apps written for specific program - Stronglifts, five3one, etc - they are nice, but once I want to switch a program again, I'd have to find a new app, all my progress in the app will be lost, it's a bummer...
So, at that point I thought - I gonna just create an app for myself. I'm a good at web development, I'll build a PWA app which I'll use from my phone, and I would code in a program I want. Programs would be pluggable, so whenever I'm tired of 5/3/1, I'll add another program, and all my progress would be saved.
I got super excited about this idea, and started to work on it during evenings.