SuperMemo
Forget about forgetting
Freeware
SuperMemo 16
v16.1 from Apr 5, 2015
Windows 7-10
Trial
SuperMemo 17
v17.4 from Jun 11, 2018
Windows 10
Trial
SuperMemo 18
v18.05 from Oct 29, 2020
Windows 10
Trial
SuperMemo 19
v19.1 2025 and on
Windows 10-11