Roller Derby Penalty Timer is the best mobile app created specifically for roller derby officials.

Typical stopwatches can be unreliable and cumbersome to use. Roller Derby Penalty Timer provides a reliable way to track penalties with built-in knowledge of the WFTDA ruleset for those tricky jammer situations. If you're short staffed at practice, managing the full penalty box is no problem!

Features:

Manage any configuration you'd like: two blockers, two jammers, four blockers, or even the full penalty box!

Stop all timers simultaneously between jams.

10 second warning, alerting you to tell the skater to stand up.

Tap-edit allows you to quickly edit a time or add a minute for a double-penalty.

Customizable colors to match the team uniforms.

Auto Airplane Mode for buying the paid version.