How should missionaries keep track of work related expenses?

We encourage our missionaries to use automated software to keep track of their work/ministry expenses. This kind of apps saves time and efforts. One of the software that some of the missionaries use is Expensify.com. In this online tool, you can always link your work Credit Card to your account, and the program will sync all the transactions you make with this Credit Card automatically. You can also add expenses manually.  Another useful tool is Abacus.com, which can automate your experience in tracking and recording expenses.