StackDays turns training for race day into something you can actually see build: log any habit, watch the days stack into a streak, and drag your friends into a challenge with you.
days, on average
Motivation gets you started. It doesn't finish a triathlon. Research on habit formation puts the average time for a new behavior to become automatic at around 66 days, not 21, not overnight.
StackDays isn't built around hype or streak anxiety. It's built around the boring middle: the version of you that shows up on day 34 when it's raining, because the app made it stupidly easy to log a half-effort swim and keep the chain alive.
No fixed checklist, no rigid plan. StackDays adapts to whatever you're actually training for.
Run, swim, meditate, read. Name it, pick a unit, set your daily goal. Fully yours, not a preset list.
Tap a checkbox or log real distance. Sync steps and workouts automatically from Health Connect or Apple Health.
Every completed day fills in your heatmap. Streak freezes cover you on the days life actually gets in the way.
Missing one day is normal. StackDays is built to get you back on day two, not let day two become day twelve.
And nothing you have to configure to get started.
Create a challenge, invite your training buddies, and track everyone's progress together with a shared team chat and leaderboard.
Steps, runs, and rides pulled in automatically from Health Connect or Apple Health.
Two free passes for the days that genuinely go sideways.
A consistency heatmap, per-habit breakdown, and a look at which days of the week you actually skip.
From your first logged day to a 46-day streak and beyond.
A daily nudge at the time you pick, plus a check-in if you're at risk of losing a streak you've been building for weeks.
Never break the streak
Crush challenges together
Watch your consistency grow
Stay accountable with friends
Unlock the full experience
Skip smart, streak stays
Free to start. No credit card. Just you, tomorrow's habit, and a streak worth protecting.