Show HN: Andi – AI language tutor with a 3D talking teacher (Realtime API)
2 thekotik 3 6/5/2025, 7:08:05 PM anditutor.com ↗
I vibe-coded Andi — a browser-based AI language tutor where you practice with a 3D talking teacher in real time.
It's built with the Realtime API, WebRTC (via LiveKit), and Three.js, Next.js plus a custom lipsync animation system. The biggest challenge was performance — running smooth 3D and real-time audio in-browser is brutal. I ended up designing a lightweight 30MB character model (down from 500MB) to make it usable on the web.
It’s desktop-only for now. Mobile browsers don't have enough performance for heavy 3d models. If browser version gets stuck, just reload the lesson. Chrome is better then Safari.
Would love feedback on: – Whether this tool can find real product–market fit in such a crowded space – How you’d approach bringing this to mobile (iOS especially)? In my experience Apple libraries don't work well for heavy hyperrealistic models. Unity seems the only reliable option rn. – Better ways to optimize or rethink this stack for 3D + realtime audio?
I watched the demo video. Obviously you're going to need to write language lessons for the avatar to deliver. I'm not sure what your background is but do you know how you'll do that? Many apps hand that job over to AI and that might work fine for a beginner lesson 1 when you're just repeating some simple phrases but how would it manage with a properly structured lesson about the present perfect or subjunctive? I've seen AI give incorrect information about grammar and create quiz questions that are wrong or impossible to answer.
Also, language lessons don't just exist in isolation, a good language course ties each lesson together to reinforce what was previously learnt. You would have to think about all this.
Your other alternative is straight-forward conversation practice for higher levels, where you're not actually teaching the language, just providing conversation. But I think that very soon ChatGPT will have human-like avatars in their interface, so people will be able to use that for conversation practice.
You're probably aware, but other apps that are doing something similar are Praktika, Loora, Call Annie, Makes You Fluent.
If you want to do some more reading about the AI language learning industry you may find my Medium articles useful: https://medium.com/@oh-yeah-sarah
So far it's a good balance I found between giving directions to agent and some space to improvise. What do you think?
Yes, competition is brutal. But if you open their product it's not even close to experience of "humanoid" tutor in a call. I tried to get to it as close as possible without performance issues, not sure if users care, but to me it's a huge difference.