Kiprun Pacer

The free answer to Runna for anyone training toward a marathon or a trail race. Decathlon's app builds a personalized plan for 5K, 10K, half marathon, marathon or trail distances, and Decathlon bills it as 100% free. After each session you log a debrief, and the app recommends adjustments to the plan based on that and your performance data. It works without a watch, but also syncs automatically with Garmin, Apple, Polar, Suunto, Coros and Fitbit, so it fits whatever device you already have. Voice guidance, advice on recovery and strength work, and Decathlon loyalty points where the program runs in your country round it out.