The best alternatives to LingoDuck are BoldVoice, Foreign Buddy, and HiNative. If these 3 options don't work for you, we've listed a few more alternatives below.
What do you think of LingoDuck?
AssemblyAI— Speech-to-Text API with superhuman accuracy
BoldVoice is an accent coaching app for non-native English speakers that helps them be as well-understood and confident in English as in their own language. You get personalized daily video lessons by a Hollywood coach and immediate pronunciation feedback.
Best Tandem is a language learning app which employs the world as your class. Learn any language you want by simply downloading the app and connecting with people from around the world who can teach you that new language.