I’m using Boostcamp at the moment: free version, not open source, and its bothering the hell out of me. Limited. Bloated. Paywalls. I love the detailed programs and routines, and have not found a similar replacement. Any recommendations that include:
Routine creating
Custom exercises
Access to existing database of workouts (most important).
If you mean weightlifting, liflog is really the best that there is right now. Beautiful interface, simple, database of exercises to add (though it is isn’t as good as something like Progression, which isn’t open source).
Programs for weightlifting are pretty simple and Jeff Nippard has great program overviews for different goals and availability, and tons of other fitness youtubers also.
If you mean something that is more bodyweight/calisthenics with video/animated explanations then I don’t know of one.