Over 160 Free Personal Information Managers – lifehack.org
The best type of software for productivity is personal information manager (PIM). They are softwares which help you oraganising your personal information, such as contacts, calendars, emails, notes etc. To give you choices, find out what are available on the Internet and fits you, Listible has a huge list (over 160) of PIMs. There are Windows & Mac based software; web based, and all of them are free: