swim.taxi

Coming soon to the App Store

A carpool app for swim practice groups.

Twelve families drive to the same pool four mornings a week, mostly in half-empty cars. Everyone knows it. It gets figured out in the group chat, badly, and the same three parents end up doing most of the driving.

For iPhone. It's free, there's no account to make, and there's no company behind it.

What it doesHow it's built

Why

What happens now.

Practice is at 5:20am on Tuesday and 7pm on Thursday, at a pool nobody lives next to. Twelve families are solving the same problem separately, in the same thread, between messages about meet entries and lost goggles.

Offers scroll away

Someone asks if anyone needs a ride Wednesday. Sixty messages later nobody can find it, including the person who wrote it.

You can't tell if Friday is covered

So either everyone drives just in case, or a kid is standing outside the pool at 8pm and two parents are both sure the other one had it.

The same three parents drive

Nobody is counting, so nobody can point at it. The reliable ones notice anyway, and after a season or two they stop offering.

Asking twice in a row feels like too much

Even when you drove four times last month. There's no record of that, so it's your word against a vague sense of who owes whom.

What it does

What actually happens.

  1. You put in the schedule and where each kid starts from

    Practices, who's going, and the pickup address for each child. You do this once at the start of the season rather than renegotiating it every Sunday night.

    On a recent iPhone, Apple Intelligence reads the season schedule off a photo of the coach's email, so you're checking it instead of typing it.

    This Week

  2. Someone needs a ride, and your phone works out who's closest to it

    You say your daughter needs picking up Wednesday. The app looks at who is already driving that night and works out which of them could get her with the smallest detour — following real roads, not a straight line on a map.

    It works the other way round too. You've got a spare seat, you say so, and you get the same list of kids you could grab on the way.

    You can change any of it, and you're the one who says yes. It never assigns anybody to anything.

    Suggested pickups

  3. Afterward, the other parent taps once to confirm it happened

    That's the whole thing. One tap, from the parent whose kid got the ride. It's the only admin the app asks anyone for, and it's kept to one tap because nobody wants paperwork after a car trip at 6am.

    Balance

Keeping track

Keeping count of who's driven.

When someone drives your child, that gets recorded. When you drive theirs, so does that. Nothing happens as a result — you can't spend it, you're never locked out, and nobody gets a notification about where they stand.

It's there so you can ask for a ride on Thursday without feeling like you're imposing, because you can both see you did the Tuesday run four times last month.

Given4·received1

That's the entire display. No color, no arrow, no suggestion about what you might do about it.

Where your data sits

There's no account, because there's nothing to sign in to.

Your group's schedule and addresses sit on your own phones and sync through your own iCloud. One parent's account holds the shared copy; everyone else gets access the normal Apple way.

I can't see any of it. Not "I promise not to look" — there's nowhere for me to look. You can check that yourself; the code is public.

How a swim.taxi group syncs One parent's iPhone signs an entry and sends it to a shared area in another parent's own iCloud. Apple tells the other phones something changed, they pick it up, check the signature and work out the week themselves. No swim.taxi server is involved at any point. Your iPhoneSigns with a key thatnever leaves your phoneA parent’s iCloudA mailbox. Moves sealedentries around and readsnone of themEveryone elseEvery phone has thewhole thing alreadypublishsigned entrynotifythen fetchChecks the signature andworks out the weekon its ownon the phone, no signal neededThere is no swim.taxi server.Nothing passes through me, because there is nothing for it to pass through.
  1. Your phone signs an entry — “I can drive Wednesday” — with a key that never leaves it.
  2. That entry goes to a shared area in one parent’s own iCloud.
  3. Apple tells the other phones that something changed.
  4. Each phone picks up whatever it missed.
  5. Each phone checks the signature and works out the week itself.

Every phone has a full copy, so the app keeps working in the parking lot with no signal and catches up later.

Everyone needs an iCloud account

That's a requirement rather than a nice-to-have. Almost every iPhone owner already has one, but if someone in your group doesn't, they'll need to set one up.

If the parent holding the shared copy leaves, you're fine

Every phone already has the whole thing. Someone else picks it up and the group carries on with the same history and the same numbers. Whoever holds it doesn't run anything or get to decide anything.

Limits

What it doesn't do.

  • It doesn't check anyone's license, insurance or driving record. You decide who drives your child, the same way you do now.
  • There are no strangers in it. Everyone in your group is someone you added, and there's no way for anyone else to turn up.
  • No money moves. The credits aren't worth anything, can't be cashed out, and can't be traded.
  • It can't tell you where your kid is right now. There's no live location in the app and no plan to add it.
  • It assumes one pool and a group that already knows each other. If you wanted a general carpool app, this isn't it.

Who made it

I built this for my own practice group.

I built this in the evenings for my own practice group. It's free, there's no company behind it, and there's nothing to sell you — which mostly means if you find a bug you're emailing one person, not a support desk.

The code is public, so anything on this page about where your data goes is something you or someone you trust can go and check.

Questions people ask →