Duolingo's North Star Metric
51+-person team · United States · duolingo.com
Their North Star Metric
Daily Active Users with a streak
Reconstructed from public sources. Not officially endorsed by Duolingo. Request edit
Why this one won
Duolingo's product is habit. Streaks are the single behaviour that correlates with learning outcomes, retention and revenue. The streak metric forces every team (content, ads, notifications, social) to align around one question: are people coming back tomorrow?
The Ray
Input metrics that multiply to produce the North Star. Tagged by dimension.
New streak starts
Acquisition
Streak length p50
Depth of habit
Sessions per active day
Daily repetition
Streak recovery rate
Win-back
What they considered and rejected
| Metric | Why it was considered | Outcome |
|---|---|---|
| Lessons completed | Output not habit | Eliminated |
| DAU with streak | Directly measures habit | Kept |
| MAU | Too loose | Eliminated |
Lessons learned
If your product lives or dies on habit, the North Star has to measure habit. Streak protection features weren't a cute feature - they were the roadmap.
Related North Stars
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Weekly active creators sharing videos
Loom's viral wedge is sharing. A video that's recorded but never shared is a private use case with zero network effect. The weekly active creator metric captures both sides - someone recorded something AND they passed it on - and is the single best predictor of team expansion.
Miro
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Weekly collaborating teams (2+ users on a board)
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Weekly engaged members (post, comment or message)
LinkedIn's business (recruiting, sales nav, ads) depends on members who actually engage with the network. Passive profile viewers don't generate the data that makes the platform valuable. The weekly engaged member metric filters out ghosts and captures the members whose engagement powers the whole business.
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