Zone 2 training app for Apple Watch with weekly leagues
- supporters
Underdog (tryunderdog.com) is a heart-rate-zone training app for Apple Watch.
What it does
Who it is for Runners, cyclists and anyone building an aerobic base who wants accountability.
Free on iPhone with Apple Watch.
Featured Today

tiun
Payments backend for indie hackers
All-in-one: Auth, payments & DB
Single command: MCP, Skills
Built for developers.
Merchant of Record. Better fees.
Join the Microlaunch builder community
Get product updates, weekly standouts, and founder deals.