Memrise is an online system that provides a variety of courses on a variety of subjects. Users can also make their own courses to revise their own information. It is entirely free to use and uses some “memory techniques”, such as mnemonics, to help learn stuff faster. In my experience it is not as efficient as Anki but it is a good tool that language learners could use.
Website – https://www.memrise.com/
Undergraduate Software Engineer and Language Enthusiast.