SidelineFor marathon runners and the people who love them
Get your people to the right kilometre.
A marathon is a very long way to run on your own. Sideline lets your friends see the whole course, pick a spot, say what they are bringing, and follow you live, so the hard part is never empty.
It has now done it for real. At the Berlin Marathon on 27 September 2026, Fritzi ran 3:58:00 with thirty-six people in her squad, twelve corners of the city covered and someone waiting at almost every kilometre she cared about.
Works today in any phone browser, with nothing to install and no account for your friends. Android and iPhone apps are coming: get told when they land.
The short version
Your cheer squad, organised.
Twenty-three seconds, sound on. You are running, your friends want to be out there, and Sideline shows you who will be where and with what, without you having to organise any of it.
Captions are in the player if you are somewhere quiet.
Why this exists
Support goes a long way. Organising it goes nowhere.
If you have ever tried to get friends out along a marathon course, you know how it goes. A group chat, a screenshot of a map, a lot of "where are you". Three people end up at the same corner and the runner does the hardest ten kilometres with nobody there.
The support is real. There is just no way to see it, plan it or share it. Sideline is that missing piece.
Who is standing where, what are they bringing, and where is the runner right now?
What it does
Everything the squad needs on one screen.
Who stands where
Cheering spots on the real course, the official ones included, with the train line to get there. Friends pick one and their face shows up on the route.
Where the gaps are
The whole course folds into a snake with everyone's face on it. The empty stretches show up, especially the brutal bit after 30 km.
What they bring
Water, gels, a banana, a jacket for the finish, a big sign, noise. Big buttons, so nobody brings three bananas and no water.
The runner, live
From the runner's phone, or from the official race tracking where the race has it. Everyone gets an arrival time for their own corner.
"I just saw them!"
One tap when the runner goes past. The whole squad gets told, the route turns green, and everyone can pile in with cheers.
Chat and a photo wall
One chat for the squad and every photo in one place, with reactions and comments. Friends who can't be there follow along from home.
A look inside
What the squad sees.
How it works
Three steps, no app store.
The runner makes a squad
Pick the race, set a goal time, and share one link with everyone who is coming.
Friends pick a spot
Open the link, tap a spot on the map, type a first name. No account, no password.
Race day runs itself
Live position, arrival times for every corner, "I just saw them" and photos, all in one place.
Where it is now
Berlin is done. Frankfurt is next.
Berlin, runFrankfurt, 25 OctoberPhone apps, soon
Sideline works right now in any phone browser, and you can add it to your home screen so it opens like an app. Berlin was the first race on it and it held up: live position from the official timing, friends confirming sightings along the way, one chat and one photo wall for the whole day.
Frankfurt on 25 October is next, and the official tracking already works there. If you are running something else, tell me which race and I will look at putting the course in.
Proper Android and iPhone apps are on the way. They matter most for runners, because a phone app can keep sharing the runner's position with the screen locked in a belt.
Which race are you running?
Leave your email and I will tell you when your course is in, and when the phone apps land. Nothing else, ever.
Who made this
Hi, I'm Ermis.
I studied computer science and then spent years doing pretty much everything except writing code. These days I build things with AI doing most of the typing and me doing most of the deciding. I am a hobbyist, not really a coder, and I have made my peace with that.
Sideline started with a friend running Berlin and one question nobody could answer: who is going to be where? It has been a great excuse to use a part of my head that sat quiet for a long time. Most of the fun was deciding what it should feel like, not how it should work.
If you try it on a race, I would love to hear how it went. There is a feedback box inside the app, and it goes straight to me.
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