C2K — Couch to 5K & 10K

C2K is a free, open-source running trainer for Android that guides you from the couch to running 5K, 10K, and beyond — with no ads and no tracking. Programs: • Pre-C25K — 3-week gentle starter for absolute beginners • Couch to 5K (C25K) — 9-week program, 3 runs per week • Bridge to 10K (B210K) — 6-week bridge for C25K graduates • Couch to 10K (C210K) — 14-week program, continues from C25K • One Hour Runner — 13-week progression from 30 to 60 minutes continuous running • 5K Improver — 8-week speed and stamina program for runners who can already complete 5K Features: • Audible voice prompts — "Start running", "Walk for 90 seconds", countdown warnings • Customizable coaching — adjust voice speed/volume, countdown warning timing, and mid-interval cues • Vibration cues as an alternative or addition to voice • Background workout timer — continues with screen off • GPS tracking (optional) — records distance and pace; works without GPS too • Treadmill mode — indoor runs without GPS • Workout history — session log with total distance, time, best pace, longest run, and calorie estimates • Progress tracking — remembers which weeks and days you've completed, with the option to reset • In-app running guide — FAQ covering pacing, gear, and terminology • Available in 7 languages — English, German, Spanish, French, Galician, Portuguese (Brazil), Russian • Works offline — no internet permission required • No proprietary services required — compatible with GrapheneOS and privacy-focused devices Permissions: • FOREGROUND_SERVICE — keeps the workout timer running with screen off • WAKE_LOCK — prevents the CPU sleeping mid-workout • ACCESS_FINE_LOCATION — optional GPS for distance/pace tracking (you can skip this) • POST_NOTIFICATIONS — workout notification with pause/stop controls • VIBRATE — optional vibration cues during workouts C2K is free software released under the GNU General Public License v3.