I've been trying to simulate the experiences that I had on those platforms with a voice agent.

You can try a demo for free here (or watch a video of me using it on the landing page):

https://lingle.ai/tryout/lingle-showcase

Right now the agent can plan a lesson with visuals and a conversation focus, guides the user through the lesson - correcting and explaining things on a whiteboard if necessary, and asks relatively engaging questions. There is also a long term user model that builds over time, that maintains memory of the user's produced vocabulary, grammar, and skills, meant to make each lesson informed by the past and build on the user's knowledge (obviously this is still relatively fragile in practice).

The voice agent itself has actually decent latency, especially given that turn detection was a bit of a challenge given that language learners often speak slowly and struggle when they're thinking, so I had to build with that in mind.

Anyways I wanted to get some feedback on the product. I think it's quite a different take on language learning tools than those that currently exist.