ExpressJS - Sinatra inspired web development framework for node.js -- insanely fast, flexible, and simple
Hevy - Simple workout logging, insightful analytics, and a growing community of gym athletes.
Chart.js - Easy, object oriented client side graphs for designers and developers.
Strong.app - Strenght training logger.
Backbone.js - Give your JS App some Backbone with Models, Views, Collections, and Events
HomeFitness OS - The all-in-one fitness system for Notion