Here is the list of top opensource and free apps to manage your finances. It much easier to use an app rather than a spreadsheet or a physical notebooks.
GnuCash
GnuCash is the most popular personal and small-business financial-accounting software, licensed under the GNU GPL. Easy to use, yet powerful and flexible, GnuCash allows you to track bank accounts, stocks, income and expenses. As quick and intuitive to use as a checkbook register, it is based on professional accounting principles to ensure balanced books and accurate reports.
OS Support : GNU/Linux, BSD, Solaris, Mac OS X and Microsoft Windows
Website : https://www.gnucash.org/
Homebank
HomeBank is a free software that will assist you to manage your personal accounting. Designed to be easy to use and to be able to analyses your personal finance and budget in detail using powerful filtering tools and beautiful charts.
OS Support : GNU/Linux, FreeBSD, Mac OS X and Microsoft Windows
Website : http://homebank.free.fr/en/
KMyMoney
KMyMoney is a cross-platform personal finance manager that helps you track personal finances. KMyMoney is Ease to use, with features found in commercially-available personal finance applications
OS Support : GNU/Linux, Mac OS X and Microsoft Windows
Website : https://kmymoney.org/
Skrooge
Skrooge allows you to manage your personal finances, powered by KDE. Thanks to its many features, it is one of the most powerful way to enter, follow, and analyze your expenses.
OS Support : GNU/Linux, BSD, Solaris, Mac OS X and Microsoft Windows
Website : https://skrooge.org/
