BillMonk is described as 'Billmonk lets you keep track of debts between friends'. There are more than 10 alternatives to BillMonk, not only websites but also apps for a variety of platforms, including Android, iPhone, Android Tablet and iPad. The best alternative is Splitwise, which is free. Other great sites and apps similar to BillMonk are ihatemoney (Free, Open Source), SplittyPie (Free, Open Source), Kittysplit (Free) and Tricount (Free).
Splid helps friends manage their money. Perfect for vacations, share housing and groups who need to share expenses, Splid keeps track of every transaction and shows who owes whom how much. It is simply the easiest way to manage group expenses.
TabSplit allows users to keep track of their "social debts". So if you go out and share a tab it’s easy to split it up between your friends and know who has paid the tab and who owes you the remaining money.