A flashcard app with a streak counter is a weekend project. A spaced-repetition algorithm tuned against hundreds of millions of learner interactions, across dozens of professionally-designed courses, is a different scale of product entirely.
VIBE SCORE 95/100
A moderate score here just means the individual parts are buildable — it isn't a build/buy recommendation on its own. Read "why CanICodeThis says Just pay" below for the actual reason this one's still JUST PAY.
The parts this build actually needs, each rated on its own — the average is the Vibe Score above.
| Landing page | 99 |
| CRUD database | 95 |
| User login | 92 |
Two real costs, not just "free": the AI agent's own usage, and hosting once it's running. Both are estimated from this app's own effort rating and component list — see the assumptions on the method page.
| AI agent — with a subscription (Claude Pro/Max, Cursor, etc.) | $0 marginal |
| AI agent — pay-per-use API, no subscription | $86–$172 one-time |
| Hosting, once it's running | $0/mo (free tier) |
| Domain name, if you want your own | ~$12/yr |
Duolingo costs $6.99/mo. Even paying per-token with no subscription, and accounting for hosting, this build pays for itself in about 25 months.
Don't feel like building it? These are already made, open-source, and free.
Just pay. A flashcard app with a streak counter is a weekend project. A spaced-repetition algorithm tuned against hundreds of millions of learner interactions, across dozens of professionally-designed courses, is a different scale of product entirely.
Duolingo costs $6.99/mo (about $84/yr) as of 2026-08. That's what a working rebuild would save you.
Course content for a full language, professionally designed and pedagogically sequenced, represents years of curriculum work you'd need to either license or write yourself Their spaced-repetition algorithm is continuously tuned against a genuinely massive dataset of real learner performance — that's applied research, not a formula Speech recognition for pronunciation practice adds real ML complexity beyond text-based quizzing
Yes — Anki are open-source options worth trying before you build your own. Details are in the standard parts section on this page.