Duolingo: How the $15B App uses Gaming Principles to Supercharge DAU Growth
Written by Vin Sathyamoorthy, former Zynga Product Manager and a Reddit Product Director. Current proud Texan, and a member of the Deconstructor of Fun consulting team. These facts aren’t mutually exclusive.
Duolingo has managed to capture the popular zeitgeist with more than 100 million monthly active users. To put its success in perspective: Duolingo’s market capitalization is 10x greater than its next biggest competitor (Babbel), and its daily active user count is similar to Discord and Twitch. It has achieved significant cultural awareness, too: Duolingo has 14M TikTok followers, is a key partner in Netflix’s Squid Games 2 marketing and was featured in the $1B global hit movie Barbie. How is an education app rivaling the popularity of media & entertainment products?
Duolingo’s rocketship user growth is because of its laserlike focus on becoming a daily habit product. Duolingo saw that daily retention was its biggest lever for user growth and subsequently, revenue growth. With a focus on getting people to use the product daily (measured via a metric called the “Current User Retention Rate”), Duolingo has 4x’ed its user base since 2020. This is an extraordinary achievement for a product that had already scaled to millions of users.
(Left) Hypothetical impact of Current User Retention Rate (CURR) on DAU growth compared to other growth levers - CURR was clearly the most impactful; (Right) Actual CURR improvements leading to a 4x DAU growth in the last five years
But how did Duolingo become a daily habit? Duolingo leveraged a critical insight: Duolingo could fit learning into the 3-5 minute “gaps” in people’s days. This is the “gap time” when people are in between meetings, waiting to pick up their kids from soccer practice, etc. Candy Crush, puzzle games, and YouTube typically occupy this time to prevent boredom. Duolingo’s thesis was to build a product that was fun, smart and consumable in 3-minute gaps.
This essay will cover the strategy that Duolingo employs to drive long-term DAU growth. We will deep-dive into three key pillars:
Meta: Duolingo’s “Meta”, or long-term aspiration, is self-improvement via language learning. When people have a very strong “Why” for using a product, it is a powerful core driver to get people to continuously commit.
Fun: Duolingo’s sessions are a fast-paced 3-5 minutes with variety, ample encouragement, instant rewards and some light competition. Language learning takes more activation energy than scrolling on TikTok or binge-watching Netflix, so sessions must offer ample surprise & delight.
Lock-In Systems: A product that offers a fun session isn’t enough to prevent user churn. You need retention systems that make a user go, “I should come back tomorrow and do this again.” Duolingo relies on streaks, leaderboards, emails/notifications and a few other systems to “lock in” users and prevent them from churning.
These elements are heavily influenced by games, and Duolingo indeed benefits from “gamification” to drive engagement and retention. Let’s go deeper into Meta, Fun and Lock-In Systems to see this gamification in practice.
Meta
Duolingo is “discretionary spend” when it comes to people’s time - they don’t have to do it. They must want to do it - and, therefore, the “why” has to be very powerful. The commitments that we make and actually keep are driven by powerful “why’s” - like the person who successfully loses 100 pounds after experiencing a heart attack and is driven to see their kids graduate high school. This is a powerful motivator - this person will keep their exercise regimen even in the face of a demanding professional life and injuries.
Having a powerful “why” gives us a reason to stick with something because of a very big payoff at the end of the journey. Difficult journeys always have highs and lows, and you need strong motivation to keep going in the face of adversity. It also allows you to see past things that might otherwise feel manipulative, and say, “I’m still going to do it.”
Duolingo sets the Meta and reinforces the Meta in a few key ways:
Meta System #1: Drawing explicit commitments from users. Duolingo asks its users to make commitments to their Meta (“why”) with measurable goals, like completing 14 lessons in the current week. The consistency bias encourages us to be consistent with commitments we made to our past selves. Duolingo PMs credit this “Commit” language to big wins in retention.
Meta System #2: Paying for Subscriptions. Duolingo asks users to make a commitment to a paid subscription in the first 1-2 days of their experience, urging them by telling them that “Super users are 4x more likely to finish the course”. Counter-intuitively, asking users to pay is better for retention. Spending money on a product is a real commitment - you have real financial skin in the game - and taking that leap is a strong affirmation of a user’s “Why”.
Meta System #3: Visualized Meta via the “Journey Map”. Much has been made about Duolingo’s learning path and how it closely resembles Candy Crush and other games. This is a powerful visual representation of a user’s “Why” - they are able to “see” the mountaintop that they are ascending towards. When we have definite and concrete representations of our goals, we are more likely to commit to them (and users are more likely to stick with Duolingo).
Meta System #4: Reminders reinforcing the “Why”. Emails, push notifications and in-app copy are all tools to reinforce the “Why” behind our learning.
Fun
With the “Meta” serving as the Engine to keep users around, “Fun” is the nitro fuel to drive the Engine. Put another way - our inner selves must be convinced both rationally AND emotionally to commit to any change. The “Meta” serves our rational side, and “Fun” serves our emotional side.
“Fun” is a loaded term, so for simplicity, I’ll define fun as any input that drives a player’s excitement in completing an activity. Fun takes on many forms: Novelty, Learning New Skills, Stimulation of the Physical Senses, Narrative & Storytelling, Self-Expression and more.
In Duolingo’s case, there are a few different systems that drive Fun:
Fun System #1: Lessons with Large Variety and “Right-Sized” Difficulty. The entire Duolingo experience hinges on its atomic unit, the “lesson”, working well. Each 3-minute lesson is composed of 8-10 parts, with each part having: (a) a new format; (b) a simple task. Formats are varied and different, like matching drills, sentence construction, and speaking practice. Each lesson “part” is a very simple task, taking 10-20 seconds to complete, so you don’t feel bored with any part of the lesson.
Crucially, Duolingo is very conscious about making lessons hit the sweet spot of difficulty. James Clear, in his book Atomic Habits, calls this the “Goldilocks Zone” - “the human brain loves a challenge, but only if it is within an optimal zone of difficulty … The Goldilocks Rule states that humans experience peak motivation when working on tasks that are right on the edge of their current abilities. Not too hard. Not too easy. Just right.”
Fun System #2: Social Play. Duolingo’s leaderboard system is a vector of progression that is not directly related to language mastery, but about relative effort to your peers. If you spend more time in lessons, you climb in your leaderboard. If you are one of the 10 highest in your leaderboard at the end of the week, you advance to a more difficult leaderboard. This creates a dynamic situation where other players can influence your own situation.
This Social Competition also follows the same principles of the “Goldilocks Rule” mentioned above - you are grouped with people of similar level as you, so it’s fun to be challenged in your own “zone” of difficulty. It’s fun to climb up a few spots with just a few extra lessons. It’s fun to see progression at the end of the week by getting promoted to a new leaderboard (or “League”, in Duolingo’s words). Leaderboards & Leagues are, of course, a proven feature in games - and lead to better engagement/retention in Duolingo, too.
Fun System #3: Generous Rewards Systems. A key component of effective games is instantaneous feedback loops to let players know if they’re doing well or poorly. Duolingo applies frequent praise and encouragement - within sessions, after sessions, and between players (users can send “Celebrations” to each other). Praise is a type of Reward that makes experiences fun.
Duolingo also has a rich Rewards system to provide different vectors of goods. XP Boosts, Streak Freezes, and Timer Boosts are all “powerups” to make your lessons better. Underpinning all of these Rewards is a Gems currency system, which can be used to buy these Rewards. Duolingo offers all these goods (XP Boost, Timer Boost, Streak Freeze, Gems) randomly for completing lessons, giving more positive feedback to users and increasing the “feel good” factor.
Fun System #4: Progression & Collection Systems. Again, dipping into the Gaming playbook - Duolingo creates Daily and Monthly Quests to encourage longer sessions and daily retention. Daily Quests give users the excitement of completing something today and drive engagement variety (Quests ask you to engage in different parts of the app).
Monthly Quests create a mid-term aspiration on top of Daily Quests - complete enough Daily Quests in a given month, and you complete the Monthly Quest (complete with a collectible badge). Quests promote fun by creating near-term aspirations, encouraging variety in gameplay, and promoting collection aspirations with Badges.
Fun System #5: Events. Duolingo taps into another Gaming system - surprise - with Events. Events add “spice” to the repetitive nature of any daily habit by mixing up the formula with some new formats. A fun format is the “XP Ramp Up Challenge” - you get progressively more difficult lessons that you complete within a 2 or 3-minute window. You have the opportunity to earn 100+ additional XP in the event, which can be a big boost in your Leaderboard progress (Fun System #2: Social competition).
Events reinforce the Core Systems, and the Core Systems reciprocate to reinforce Events - for example, one of your Daily Quests (Core System) could ask you to complete one XP Ramp Up Challenge (Event). Collectively, they gently nudge you to complete more lessons - or increase your engagement with Duolingo.
Lock-In Systems
The final piece of the puzzle is getting users to come back the next day - this is where “Lock-In Systems” come into play. You could alternatively call this “Retention Systems” - having a great Day 0 session with lots of engagement is great, but it’s no good if users don’t return on Day 1, Day 2, etc.
Duolingo has instrumented a number of Lock-In Systems to ensure that players feel the itch to come back on a new day.
Lock-In System #1: Streaks. Duolingo Product Managers credit Streaks for being the product's most important lever in driving DAUs. Duolingo has 9M users on the platform with a streak lasting a year or longer. Streaks are ridiculously simple in conception - you do lessons every day and you maintain your consecutive days’ “streak”. There’s a strong “loss avoidance” psychological factor here, but what makes Streaks very potent is that its effect is stronger as time passes. You might not care about losing a 5-day streak, but you’d certainly feel some pain about losing a 1000-day streak.
An important note on Streaks: it is potent because people care about the Meta: self-improvement via language learning. When apps don’t have a strong Meta and use Streaks, it is a much weaker mechanic. The combination of Streak + Strong Meta makes this a winner.
Lock-In System #2: Social Pressure. Friends don’t let friends down - this is the driving principle behind Duolingo’s biggest social features, “Friend Quests” and “Friend Streaks”. “Friend Quests” is a social co-op where you complete quests together before a given deadline. “Friend Streaks” is a fresh spin on the core “Streaks” product that rewards users for sticking with a Streak together (e.g. you might have a 200-day streak, but you could have a 50-day “Friend Streak” with your buddy Sally). This light social pressure works as you don’t want to let your friends down, especially acquaintances you might not have kept in touch with in a while!
Lock-In System #3: Status Pressure. The Leaderboard system creates tiers of status by allowing players to move up or down in “Leagues”. This League’s class system (e.g. Ruby, Emerald, Pearl, Diamond) creates an aspiration weekly - every week provides a fresh opportunity to get promoted. This creates two types of Status Pressure: (1) Rank at the top of your current leaderboard to get promoted; (2) “Keep up” with your current leaderboard so you don’t lose hard-earned progress, i.e. get demoted. This Status Pressure locks you into Duolingo - log in every day and compete, lest you lose that precious accumulated status (“I’m a Diamond member, Pearl is beneath me!”).
Lock-In System #4: Time Pressure. Several different features in Duolingo create time scarcity to ensure you come back at a particular time. “Daily Chests” are a feature that runs on a 24-hour clock - you can earn one in the morning (“Early Bird”) and one in the evening (“Night Owl”). It is highly retentive because it makes you come back to earn your next one, and then the actual reward is dispensed 9-10 hours later - so you better come back to claim that reward you earned! The Timed Chests mechanic is, of course, well-developed in free-to-play games.
To round out a few other Time Pressure systems: (1) “Happy Hours” are higher XP earning windows on Saturdays; (2) Special Events are capped to 1-3 hour windows; (3) Leaderboards end weekly at a fixed time, so users rush in the last few hours to ensure they keep their spot or get promoted to the next League.
Lock-In System #5: Emails, Notifications and Widgets. All of the above Lock-In Systems need delivery systems outside of the app to remind users to come back to the app. Duolingo has spent enormous resources in iterating their Email, Push Notification and Widgets systems to push the message. These Reminders keep you going, and leverage clever copy, emotionally manipulative characters and loss-aversion to bring you back. Again, as noted with “Streaks” - all of this only works because the Meta is strong. You’re ok being emotionally manipulated because you want to improve - the ends justify the means.
Conclusions
Duolingo’s relentless focus on Daily Retention creates a compounding effect that is generating huge DAU wins - as a public company, they grew by 50% in the last year to 37M Daily Active Users. This Daily Retention is driven by a focus on Meta (“why do I do this?”), Fun (“why am I excited to do this today?”), and Lock-In Systems (“why should I come back tomorrow?”).
In this essay, we covered a lot of the systems and features that make up Meta, Fun and Lock-In. Here are some generalized principles that can be applied to many different types of consumer apps:
Start with a very strong “Why”, and deeply embed that messaging in the product experience. People are more likely to stick with product experiences where the Why resonates in a deep way: like eating healthier, exercising daily, or reading weekly. Make sure this value creation is reinforced continuously in-app. A Strong “Why” also lets you introduce other features that will resonate (e.g. Streaks, Daily Email Reminders).
Make the atomic unit of your experience small and easy to consume. This is particularly true for mobile-first products. Duolingo can easily fit into small pockets of time because our devices are always with us, like when we’re waiting in line at the DMV with nothing better to do.
Social Play and Events are fun and transcend game experiences. Duolingo is a great example of this, but we can see this trend in other places, too. Nike’s SNKR app showcases social competition with limited-quantity sneaker drops. TikTok Challenges create fun social experiences that anoint winners.
Social Influence & Loss Avoidance are powerful Engagement Drivers. We are inherently social creatures, so when we are in a position where we’re “letting the team down”, we rise up to the occasion. Similarly, we want to preserve the things that we built up, even if they feel a little silly out of context (e.g. a 500-day Streak). Systems designed with these principles in mind work.
Artificial “Time Pressure” can drive retention in non-gaming contexts, too. Streaks, Events and Timed Chests don’t just work in games. Duolingo’s usage of game-like core loop and game-like currencies allows these systems to work as naturally as they do in free-to-play games.
These principles have let Duolingo capture millions of users’ time on a daily basis. Their monetization models reflect that - 75% of revenue comes from subscriptions, followed by 9% with ads. Duolingo’s model is built on the idea that if they can get people to engage, a small percentage will naturally monetize - it is exactly the free-to-play games model. It’s no coincidence that their engagement model and business model both resemble mobile F2P so closely.
The longer arc for Duolingo in terms of long-term engagement is making sure there’s enough learning content for people beyond a single language - they want users to learn multiple languages, and non-language subjects like math and music. Duolingo’s reliance on gaming principles allows them to tackle their most important challenge: motivating users to learn.
If you’re thinking “wait, can we do this too?” — yeah, you can.
We’ve pulled together the exact systems that drive retention at products like Duolingo into The Engagement Handbook. It’s free, it’s tactical, and it’ll help you start building your own playbook.
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