Buxfer is a service that lets group of people track shared expenses.
Idea inspired by the actual company Buxfer

For each expense, Buxfer records the person who paid the expense and the expense cost. It al lows group members to examine the amount that individuals have paid, look at the history of all transactions, or determine the group member that is currently owing the most.

add_group group_name
Register a new group with name group_name

list_groups
List the names of all groups that are currently registered.

add_user group_name user_name
Register a new user with name user_name as a member of group group_name.

list_users group_name
List the names of all users of group group_name together with their current balances (i.e. how much each has paid so far), sorted by their balances (lowest payer first).

user_balance group_name user_name
Return the balance of user user_name in group group_name

remove_user group_name user_name
Remove user user_name from group group_name

underpaid group_name
Output the name of the user in group group_name who has paid the least.

add_xct group_name user_name amount
Add a new transaction for group group_name. The transaction is paid by user_name and the amount is amount.

recent_xct group_name num_xct
List the num_xct most recent transactions for group group_name.

quit
Shut down buxfer