Learning and careers decision
Duolingo Super
A limited, useful subset (serving lessons, progress tracking, offline caching, and audio) is realistic for a small team to build and maintain, but reproducing Duolingo Super's full content catalogue, polish, and ecosystem is not practical without major content and product investment.
Visit website↗Open-source builds that already do this
Every project below is open source and already does this job today. Fork one, self-host it, or take the parts you need — the build prompt further down assumes an empty file, and this is the shortcut past that. Licences differ; check the one on each card before you ship.
What a replacement has to do
- Deliver short interactive lessons, track user progress and streaks, and play/serve lesson audio for listening/speaking practice.
What it still won’t have
- Proprietary course authoring and curation at Duolingo scale
- Large catalogue of polished content and human-tested exercises
- Established mobile apps and ecosystem integrations
- Brand recognition and marketing reach
What remains hard
- Product polish and ongoing maintenance
First-year cost
Keep paying
Paying is—cheaper in year one.
On cash alone, building overtakes the subscription at 5 seats.
Money you would actually spend
Time you would spend
—
What you would spend
What we assumed
The verdict above measures whether you could build it. This one is only about money.
Runnable build prompt
Build a minimal self-hosted language-learning subscription product using Next.js (React) for the frontend, a Postgres database, and a Node.js/Express backend. Implement: (1) email/password auth and a subscription flag (no payment integration required), (2) a lesson schema and an API that serves ordered lesson steps and records step completion, (3) per-user progress tracking (XP, streak counter) stored in Postgres with migrations, (4) audio hosting and playback endpoints that serve MP3 files (support local storage and an S3-compatible backend), (5) a PWA-enabled client that caches lessons for offline access and resumes progress when online. Out of scope: full mobile native apps, large content authoring UI, analytics dashboards, and payment processing. Include automated tests for lesson API and auth flows, basic error handling and retries for audio fetches, and a README with deployment steps using Docker Compose.
How we checked
How the score was reached
- Partly verdict base52
- An open-source build was found+5
- 3 cited sources+3
- 3/3 assessment runs agreed+4
- Evidence score64
The base comes from the verdict. Everything under it is a check that either happened or did not, and each one is a fact frozen in this record rather than a judgement made at render time — so the same evidence always produces the same number.
How scoring works →Cited sources · 3
Every page the run actually retrieved.
- official productDuolingo
- open sourcemengxi-ream/read-frog
- open sourcelingdojo/kana-dojo
Integrity checks
What held up, and what did not.
