Serious endurance training should not require renting your own training history back by the month. OpenAthlete plans your season as blocks, weeks, and sessions, with A, B, and C races marked and illness or travel periods that move the sessions they cover. You build structured workouts from your own zones, pace, power, heart rate, or percentages of VMA and FTP, save them to a reusable library, and send them straight to Garmin, COROS, and Suunto watches at the next sync. Completed activities arrive from Garmin, COROS, Suunto, Polar, and Strava, or as FIT, GPX, and TCX files, and each interval is graded against what was planned. Analysis covers detected climbs, time in zones, aerobic decoupling, gradient-adjusted pace, and weather, with non-destructive fixes for heart-rate spikes. Progress views track records by distance and duration, critical speed and power, and fitness, fatigue, and form projected over your upcoming sessions, alongside HRV, resting heart rate, and sleep from your watch. Coaches see compliance, volume, and form for every athlete on one screen, get alerts for reported pain or inactivity, and exchange comments and real-time chat with athletes. A calendar feed keeps Google, Apple, and Outlook in step, and the web app installs on your phone home screen. Running on a dedicated VPS on RepoCloud with guaranteed CPU, RAM, and SSD, full root SSH access, and a browser serial console. AGPL-3.0 licensed.