The greatest free fitness app for runners is Map My Fitness, also known as Map My Run, because of its extensive GPS tracking and other free features. While we're talking about free features, Amanda Capritto, CPT, CNC, CES, CF-L1, our tester, says the monthly subscription, which costs less than $6 per month and includes analyses for heart rate, power output, running cadence, and other things, can be worthwhile.