Run against something
Race your ghosts and your friends, or run with a trainer.
CoRunner records every step, then lets you race a previous run or a friend’s recording on any route, or run with a trainer. Hills count: the comparison is by real effort, not just distance, so a climb is worth what it costs. Walks, hikes and rides count too: pick the sport on the phone, and every activity gets the same effort treatment.
Test build: allow installs from your browser when asked. iPhone version is planned.
Record
Start a run with the phone in your pocket. CoRunner logs every second, works offline, and survives an app kill.
Pick an opponent
A ghost of your own run on the same route, a friend’s recording, or a trainer: Calm, Scientific or Army.
Race by ear
The voice tells you when the opponent closes in, when it is about to overtake, when you pull ahead, and what the next hill costs.
What you hear
- “Anna is 10 meters behind you.”
- “Anna is about to overtake you.”
- “Anna passed you.”
- “Climb ahead, 6 percent for 300 meters.”
- “You passed Anna. 5 meters ahead.”
- “Halfway. Gap 12 seconds, effort pace 4:52.”
Every threshold, the rate limit and metric or imperial are yours to set, on the phone or here.
Hills count for what they cost
| Grade | Cost | 1 km counts as |
|---|---|---|
| −10% | 0.60 | 600 m |
| −5% | 0.76 | 760 m |
| 0% | 1.00 | 1 km |
| +5% | 1.30 | 1.30 km |
| +10% | 1.66 | 1.66 km |
Minetti et al. 2002, energy cost of running by grade. A trainer at 5:00 min/km slows to about 6:30 min/km on a 5% climb, like a real runner. Walks use Minetti’s walking cost curve; rides a gradient placeholder until power support.
Trainers
Run with a trainer: Calm, Scientific or Army
Calm
Keeps your pace, or one you set, and waits when you drop back.
Scientific
Follows a plan: a warm-up, a steady middle and a faster finish.
Army
Pushes: a little faster than you, with surges, and loud about it.
Voice only
Phone in the pocket. Nothing to look at.
Live map
You, the opponent and the elevation strip, on the phone or an armband.
Glasses and AR
Display glasses or the phone camera show the opponent at the right bearing. In development.
Friends
Race the people you know
Challenge a friend to beat one of your runs: they race your ghost when it suits them and the result lands on both phones. Every Monday the friends leaderboard starts from zero, ranked by effort metres, so a hilly 5 km stands next to a flat 10 km. Nothing is public unless you share it.
Questions
Is it free?
Yes. While CoRunner is in testing everything is free, live races, glasses and heart rate included. Ghost races, trainers and challenges stay free for good. See the pricing page in the footer.
Do I need to hold the phone?
No. Voice guidance is the primary surface. The live map, phone AR and display glasses are optional ways to see the same race.
What is effort?
Flat-equivalent distance. Each metre is scaled by the energy cost of its grade using the Minetti running model, so a climb counts for more and a descent for less.
Can I race a friend who lives elsewhere?
Yes. Effort challenges compare effort meters over the same elapsed time, so you can race on different routes.
What about my location data?
Runs are private by default and visible to friends only if you choose. You can export everything or delete your account from settings.
iPhone?
The Android app is here now. iOS comes after live races; the shared Rust core makes the race logic identical on both.
What is a trainer?
A runner the app plays beside you when there is nobody to race. Calm keeps your pace and waits, Scientific follows a plan, Army pushes. Each sets its pace from your recent runs.
Ready to lose to yourself?
Create an account, install the app, record one run. Your first ghost is waiting on the second.