Introduction

Duolingo grew 4.5 times by fixing user drop-off and boosting daily engagement using data, smart design, and habit-forming features.

What's the problem it solves?

Duolingo had millions of users but was growing slowly. The challenge was keeping people coming back every day and finding new ways to grow without relying on ads or copying others blindly.

Quick Summary

Duolingo faced a growth slowdown in 2018. Instead of only trying to get more new users, they focused on keeping current users active every day. Early attempts to copy popular features from games and apps like referral programs or game mechanics didn’t work because they weren’t a good fit for Duolingo’s unique product.

After these failures, the team built a clear model to understand user behavior and learned which parts of the app actually helped users come back. They discovered that improving one metric-how many users return every day-had the biggest impact. This led to smart changes like new leaderboards, better streak rewards, and carefully tested notifications. These changes helped users stay motivated and built habits that lasted. Over four years, Duolingo’s daily users grew 4.5 times, helping the company go public.

Key Takeaways from the article

• Copying features from other apps doesn’t always work; context matters.
• Daily user return rate (CURR) was the biggest growth driver.
• A simple model helped the team focus on what truly mattered.
• Features like streaks and leaderboards worked because they matched how users already used the app.
• Notifications boosted activity but were carefully managed to avoid annoying users.
• Growth came not from one big win, but from many smart, small changes tested over time.
• Duolingo’s biggest success was turning daily practice into a fun, repeatable habit.

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