Intervals.icu integrates with Strava and automatically analyzes your rides, runs, swims and other activities (with and without power). It provides basic and advanced analytics and planning in an easy to use web interface with support for desktops, phones and tablets. Follow your friends and help them progress, track your FTP without doing tests, coach other athletes, communicate with the built in chat, build a workout library (for outdoor, Zwift and others) and plan your training!
Intervals.icu is free but support on Patreon and once off donations via Paypal (no account required) are very much appreciated and go towards running costs! Supporter feature requests move up the todo list!