tandem: vlog together

You and your friends get buzzed at the same moments and each film a quick clip. The day turns into one vlog that everyone styles and keeps.

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Inspiration

My friends and I wanted to make one of those vlogs where you see what everyone is doing every hour of the day. Some of my friends were in different countries, so we couldn't just film it together. We also wanted it to look good, like the edits people actually post. That's where tandem came from, and it's why styles are such a big part of it.

What it does

You start a vlog with up to five friends and pick how often it buzzes: every hour or every two. Each time it buzzes, everyone films a quick clip of wherever they are. When the vlog ends, tandem stitches the clips into one tiled vlog, moment by moment, with everyone's day side by side. There's a widescreen layout for horizontal clips. Each person styles their own copy and exports it right on their phone.

How I built it

I'm an electrical engineering student, and before this I didn't have much software experience. tandem is my first app and the first thing I've built on my own. I built it with Claude and other AI tools. They wrote a lot of the code and taught me how the software side works as we went.

It's an Expo / React Native app with a Supabase backend, RevenueCat for tandem+, and a video renderer written in Swift that runs on the phone.

Challenges I ran into

A lot of people online make vibe coding an app sound super easy. It wasn't. Even with AI writing a lot of the code, I still had to learn how everything fits together: accounts, push notifications, the database, subscriptions, App Store review, and crashes that only show up on a real phone.

The hardest technical problem was making the export match the preview. Exports used to render on a server, and I moved them onto the phone. That meant the styled preview in the app and the final video were drawn by two different pieces of code, one in React Native and one in Swift. The fix was to work out the layout once and give both the exact same numbers, so what you see when you pick a style is what you get when you export.

The other big one was making every style work for any group. A vlog can have one to six people, a grid or widescreen, and names, times, notes and locations switched on or off. Someone always misses a buzz too. Every style has to lay itself out for all of that, and a missed clip shows up as an empty tile instead of breaking the layout.

What I learned

Building tandem is what made me fall in love with software, and with building things with AI. Before this I wouldn't have known where to start on an app. Now I have one on the App Store.

What's next for tandem

  • Bring the Android version out of closed testing, with tandem+ on Google Play at the same prices.
  • More styles and other optimizations.
  • Get real people using it. tandem launched quietly in August, and I'm starting to market it now.

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