Ledger is a powerful, double-entry accounting system that is accessed from the UNIX command-line. Ledger, begun in 2003, is written by John Wiegley and released under the BSD license. It has also inspired several ports to other languages.

To get started with Ledger, add transactions to a text file in Ledger’s own textual format. Here’s what a single transaction might look like:

2015/10/12 Exxon
Expenses:Auto:Gas $10.00
Liabilities:MasterCard $-10.00

You use the ledger command line program to see the balance of your accounts: