Support Raising Solutions has put together an article and comparison chart to help missionaries choose supporter management software that will be suitable for their particular needs.
TntConnect is a free support raising tool that is available in 15 languages, supports multiple currencies, and helps missionaries manage their relationships with their ministry partners. It can be installed on Windows or Mac.
Donor Manager is a free Windows based software for missionaries that allows supported workers to manage their mailing lists, track information about their ministry partners as well as pledges and contributions, and print reports.
MPDX is a supporter management tool that is free to missionaries, helping them manage contacts, appointments, and tasks. It can integrate with Google, MailChimp, and PrayerLetters.