duolingo
A language-learning app publicly released in June 2012, featuring multiple courses.
In July 2024, there was a collaboration between Duolingo and Genshin Impact, which had Duo (duolingo) and Klee (genshin impact) as friends.
Characters
* Duo (duolingo) (the service's main mascot)
* Lily (duolingo)
* Zari (Duolingo)
* Bea (Duolingo)
* Junior (Duolingo)
* Oscar (Duolingo)