Solo founder here. I've worked on Lex during the past few months, since no existing language learning app that I was aware of, matched my needs. Duolingo is a game, Anki is an app with a lot of power but not a lot of style, and immersion apps are out-of-date.
Lex is a quiet workplace of 34 languages. In addition to vocabulary (spaced-repetition + 5 exercise modes), there's an essay editor with real prompts and (on the highest tier) AI feedback + CEFR level estimates, and a reading section for pasting any text and getting word lookup with one click.
Current tech stack: Next.js 16, Postgres/Neon, Supabase auth, OpenAI as AI features, DodoPayments as MoR, hosting it on AWS App Runner, with Cloudflare in front.
3-day trial, no card needed. $4/$9/$19 tiers.
These are things that I'd really appreciate feedback on:
1. Should there be a tier split (Basic / Pro / Max) or should some of the Max features come down?
2. What are your expectations of feedback from the apps in this space and how does the AI essay feedback measure up?
3. Any obstacles to sign-up to first-word.
Thanks for looking! Will answer any questions happily.