How Buddy Check On Me Works
(Behind the Scenes)

Buddy Check On Me is designed as a mobile app with a SaaS backend. There are three actors: the app user, their buddies, and the backend service. These three work together to keep buddies in the loop about activities.

The system works in two modes: Private Mode (buddies are only alerted if the timer expires) and Sharing Mode (buddies receive updates during the activity).

Private Mode

In Private Mode, buddies are only alerted if the timer expires. The diagram above shows Private Mode with two different user stories:

• John’s story: John goes hiking and sets a timer for 1 hour. Both his phone and the backend start the countdown. Even if he turns off his phone, the backend keeps the timer in sync. John finishes early, completes the activity with 5 minutes to spare, and no alerts are sent. His buddy Albert never gets notified because John wrapped up on time.
• Nick’s story: Nick sets a timer for a 30-minute drive. The backend also counts down. Nick forgets to stop the timer, so when it expires, his buddy Fred receives an SMS letting him know Nick didn’t complete the activity. Fred can follow up however makes sense.

This design keeps things lightweight: users set their timers, the backend keeps everything in sync, and buddies are only brought in when needed.

Sharing Mode

In Sharing Mode, buddies are actively kept in the loop about an activity. Alongside the backend service, the app user’s phone can send direct SMS updates to buddies. This way, buddies know right away when an activity begins and when it’s completed, without waiting for a timer to expire.

• John’s story: John starts a hike and sets his timer for 1 hour. In Sharing Mode, his buddy Heather immediately gets an SMS saying “Hiking, timer: 1 hour.” When John finishes after 55 minutes and marks the activity complete, Heather gets another SMS saying “Done, 55 minutes.” Since John completed on time, no further alerts are needed.
• Nick’s story: Nick sets a timer for a 30-minute drive. His buddy Fred immediately gets an SMS saying “Started Driving, timer: 30 minutes.” Because Nick doesn’t stop the timer in time, the backend service sends Fred an additional SMS alert when the timer expires. Fred already knows Nick was driving and has the context to decide how to follow up.

This design keeps things lightweight: users set their timers, the backend keeps everything in sync, and buddies are only brought in when needed.

Key differences in Modes

• Private Mode: Buddies are only notified if the timer expires.
• Sharing Mode: Buddies get direct updates at the start and end of activities, plus alerts if timers expire.

This makes Sharing Mode useful when buddies want to be more involved in real time, while Private Mode is better when buddies only need to step in if something goes overtime.