I built an app because I kept checking my portfolio at red lights

I realized I had a bad habit.

Every time I stopped at a red light, I’d check my portfolio. Not because anything meaningful had changed, just because it was there. Most market apps are built for active checking, but most of us are just…waiting for something relevant.

So I built something for the opposite behavior.

Instead of checking, you listen.

I made an iOS app called StockCar that turns a portfolio (stocks, crypto, etc.) into a short, auto-generated podcast. It pulls in price moves and relevant news, then generates an audio update you can play while driving, walking, whatever.

A few decisions I made early on:

• No accounts. I didn’t want to deal with storing financial data, and as a user I wouldn’t trust it anyway.

• Optional position sizes. If you add them, it’ll personalize gain/loss commentary, otherwise it stays high-level.

• Caching + refresh. Generating audio is expensive, so episodes are cached and then refreshed over time.

• “Radio mode.” It’ll just keep playing updates across your portfolios so you don’t have to touch your phone.

The hardest part so far hasn’t been building it, it’s balancing cost vs usefulness.
Every time someone hits play, there’s real AI cost behind it, so I’ve had to think a lot about:

• how often updates should refresh

• how long they should be

• what actually makes an update worth listening to

There’s an optional subscription for more frequent updates, mostly to cover those costs.

I’m still figuring out:

• whether people want more frequent, shorter updates or fewer, richer ones

• how personalized the content should get before it feels creepy

• whether this is something people use daily or just check in on occasionally

Would love feedback from anyone who’s tried building something with ongoing AI costs, or anything about the concept in general.

Happy to share more details if helpful.