The short answer
Splitser and MySharedXP do the same core job: everyone adds what they paid, and the app works out who pays whom with as few payments as possible. Splitser is the established choice, with native apps and paying back through iDEAL, Wero or Bancontact. MySharedXP suits groups that pay in other currencies, want receipts read automatically, or want budgets and recurring expenses next to the shared balance.