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I'm in a similar position and recently looked for an alternative due to the recent change to limit it to 3 expenses per day.
We've ended up on https://ihatemoney.org/ for now and I use an android app moneybuster, which is available on fdroid (and google play I think).
Im not saying its the best replacement yet, but it has done our needs recently.
Edit: I've just double checked and above are both open source and there is an iPhone app also
This is exactly what I am looking for, thanks!
Potentially skim through awesome-selfhosted's budgeting section as well just in case, although at a glance it looks like ihatemoney is the one standout service that fits your use case anyway
I've created a Google spreadsheet to accomplish this sort of thing: Split Payment Calculator
It's got formatting and locked areas to help layman usage, but it's ofc still a spreadsheet UI and not a dedicated app. A bit of math proficiency and spreadsheet formula knowledge helps.
Could be replicated on other spreadsheet software like Excel or Calc, although Sheets solves a lot of problems at once, like accessibility, sync, versioning, sharing, etc
https://splitio.vercel.app/ has a great concept beeing a p2p webapp. Sadly it is very limited in functionality and has not been updated for quiet a while.
I moved to Splid and found it a bit less clear than Splitwise but better in other ways once I'd figured it out. It's not FOSS, unfortunately, but I do trust it much more than Splitwise.
Kitchenowl can do that as well and eeplaces “bring” for me (recipes/grocery list) - but it is still in early development. Native ios and android apps though!
Is there a reason you don’t just get a joint bank account (or credit card)? Put equal amounts in each month and use that for all shared expenses. Zero effort, totally fair.