Podcast Summary:

Sub Club by RevenueCat — Why Your Free Users Are Your Real Growth Engine
Guest: Cem Kansu, Chief Product Officer at Duolingo
Hosts: David Barnard & Jacob Eiting
Release Date: January 21, 2026

Episode Overview

In this episode, David Barnard interviews Cem Kansu, CPO at Duolingo, about the app’s monetization evolution and the crucial role free users play in driving growth. They explore why Duolingo resisted the “premium trap,” the surprising impact of free trials (even for freemium products), tactical lessons from A/B testing, and how maximizing free user value is essential for sustainable growth.

Key Discussion Points & Insights

The Early Days: Monetizing a Free Platform

• Duolingo’s First Model:

  • Duolingo began as a free website leveraging user translations for revenue through a crowdsourced model (e.g., translating news articles for outlets like CNN and Buzzfeed) ([01:30]–[02:08]).
  • Problems Faced:
    • Translation market was a “race to the bottom” on pricing.
    • Quality of language-learner translations proved unreliable.
    • The business drifted away from education toward translation.

• First Monetization Experiments:

  • Initial revenue tests included selling “streak repairs” (restoring a lost usage streak).
  • Ads were added as Duolingo’s user base grew, despite an earlier public commitment to “never have ads, never in-app purchases, and never subscriptions” ([02:08]–[03:40]).

Notable Quote

"Duolingo’s mission is centered around providing access to education... We realized there’s a way to provide access, but monetize the bells and whistles."
— Cem Kansu [04:10]

Introducing Ads: Balancing Monetization and User Experience

• Strategies for Minimizing Backlash:

  • Ads shown only after lessons, never during or before ([08:00]).
  • Ensured all team members dogfooded the product, experiencing ads as a user would.
  • Measured community feedback and compared complaint volumes versus other topics (e.g., complaints about missing languages were 3× greater than ad complaints).

• Ad Quality Concerns:

  • Extremely strict about blocking gambling, sketchy, or non-family-friendly ad categories ([12:14]).
  • Moved towards custom, direct partnerships to create higher-quality, brand-safe ads featuring Duolingo characters ([14:00]).
  • Internal (house) ads for Duolingo subscriptions now prioritized where possible.

Notable Quote

"With anything that's even slightly dicey, we blocked all those categories. Even if it might be a revenue loss, it’s more important to have a good user experience." — Cem Kansu [12:25]

The Subscription Journey

• Origins of Duolingo Plus (Now Super/Max):

  • Prompted by user requests to “please let me pay to remove ads.” ([24:15])
  • Early experiments included one-off purchases for ad-free months. Uptake was surprisingly high.
  • Initially, subscription offered only ad-removal, offline access, and a “support our mission” line as a third feature.

• Evolution of Subscription Offering:

  • Integration of core app mechanics (e.g., unlimited Hearts/Energy for mistakes, custom Practice Hub) behind the paywall increased retention and conversion ([33:12]).
  • Continuous A/B testing of every element: from copy-strings to purchase flows.

• Free Trials Work (Even for Freemium):

  • Initially reluctant, Duolingo found that offering a free trial dramatically increased conversion, even for a product that’s largely free ([27:57]).
  • Simply lowering payment “friction” with a trial has a large effect on skeptical users.

Notable Quote

"It just removes the payment hesitation so it lowers the barrier to entry. That’s the real benefit of free trials." — Cem Kansu [28:41]

A/B Testing and Conversion Optimization

• Button Copy That Sells:
  • Small change in “try for free” to “try for $0.00” led to a meaningful uplift in both trial starts and conversions to paid ([31:43]).
  • Emotional resonance and clarity outperform strictly logical language.

Memorable Exchange

David Barnard: "Just changing try for free to try for $0.00—you saw a meaningful uplift in conversion, correct?"
Cem Kansu: "Correct."
— [31:43–32:00]

• Continuous Experiments:
  • Over 400 A/B tests typically running across the app at any given time, with a fraction focused on monetization ([29:49]).

Strategic Free vs. Paid Feature Allocation

• Free Users as Growth Engine:

  • Duolingo’s primary growth comes from word-of-mouth. The better the free experience, the stronger the engine ([36:09]).
  • Occasionally, paid features are moved to free (e.g., Practice Hub, Explain My Answer) if the business case supports user growth long-term.

• Decision Process for Moving Features:

  • Willing to absorb revenue losses for the sake of growth or user happiness, even if those gains are less easily measured ([37:44]-[40:48]).

Notable Quote

“If you only always go by positive revenue metrics, you will burn yourself to the ground... Growth stops. What’s most important is our user growth engine keeps growing.”
— Cem Kansu [39:02]

Principle

"Take the long view. You can build a very profitable company for two years with heavy monetization, but that’s not our goal. We want to build a company that will be around in 100 years."
— Cem Kansu [42:54]

Becoming a Multi-Product Company

• New Subjects Added (Math, Music, Chess):

  • Selection based on market need, teachable/engaging mobile format, and internal expertise/passion ([45:00]).
  • Experimented with separate apps (Duolingo Math, ABC) before realizing integrating all into a mega-app was best for engagement and user discovery ([46:51]–[49:12]).

• Product and UX Challenges:

  • Extensive prototyping and dogfooding to squeeze quality learning experiences into limited mobile real estate ([50:04]).
  • Realizes many users still don’t know about Duolingo’s new subjects—surfacing this content remains partially unsolved ([53:03]).

Competition & AI

• Biggest Competition:

  • Other screen time (Instagram, YouTube, TikTok) rather than other education apps ([53:17]).
  • Fun is a necessity; otherwise, users will churn to more entertaining apps.

• AI as Friend, Not Foe:

  • AI enables better content, more features—like video calls with characters for language speaking practice ([55:08]).
  • Does not fear that AI (e.g. auto-translation) will eliminate the need to learn languages; demand is intrinsic and multifaceted.

Notable Quote

“This is similar to when calculators came out. We didn’t stop teaching math. The need to learn languages does not disappear even if you have massively good automatic translation.”
— Cem Kansu [55:53]

Contrarian Takes & Product Lessons

• Don’t Build for a Persona:
  • For massive consumer products, personas are too limiting; must serve the general population to reach scale ([57:54]).
• People Don’t Read:
  • Mobile user attention is tiny; visuals and UX, not copy, drive funnel success ([59:25]).
• Don’t Take User Feedback at Face Value:
  • Building a human tutoring feature (as requested by users) failed spectacularly because most users were too intimidated to use it ([61:36]).

Quickfire: Biggest Win & Fail

• Biggest Win:
  • Video Call feature using AI characters for speaking practice—improved actual language speaking skills in a way previous features hadn’t ([60:45]).
• Biggest Fail:
  • On-demand human tutoring failed due to user reluctance, despite high request volume ([61:36]).

Standout Quotes & Moments with Timestamps

• "Duolingo’s mission is centered around providing access to education... We realized there’s a way to provide access, but monetize the bells and whistles." — Cem Kansu [04:10]
• "If anything is even slightly dicey, we blocked all those categories... Even if it's a revenue loss, it’s more important to have a good user experience." — Cem Kansu [12:25]
• "It just removes the payment hesitation so it lowers the barrier to entry. That’s the real benefit of free trials." — Cem Kansu [28:41]
• "What you say in the purchase button makes a massive difference on your revenue curves…try for $0.00 performed really well." — Cem Kansu [31:43]
• “If you only always go by positive revenue metrics, you will burn yourself to the ground... What’s most important is our user growth engine keeps growing.” — Cem Kansu [39:02]
• "Take the long view. You can build a very profitable company for two years with heavy monetization, but that’s not our goal. We want to build a company that will be around in 100 years." — Cem Kansu [42:54]
• “This is similar to when calculators came out. We didn’t stop teaching math... The need to learn languages does not disappear.” — Cem Kansu [55:53]

Timestamps for Major Segments

• [01:30] — Early Monetization Models (Translation Service, Streak Repair)
• [08:05] — Adding Ads, Handling User Complaints & Retention
• [12:14] — Ad Quality: Blocking & Direct Partnerships
• [24:03] — Introducing Subscription (Duolingo Plus)
• [27:31] — The Impact of Free Trials on Freemium Products
• [31:43] — Button Copy Experimentation: “Try for $0.00”
• [36:09] — Moving Paid Features to Free: Growth & Value Equation
• [42:54] — Duolingo’s Long View: Avoiding The Premium Trap
• [45:00] — New Subjects (Math, Music, Chess): Why & How
• [53:17] — Real Competition: Other Screen Time, Not EdTech
• [55:08] — AI as an Accelerator, Not a Disruptor
• [57:54] — Contrarian Takes: Personas & User Reading
• [60:45] — Biggest Win: Video Call for Language Practice
• [61:36] — Biggest Fail: Human Tutoring Feature

Final Thoughts

This episode offers a masterclass in freemium product monetization, striking a balance between sustainable business growth and providing lasting value for free users. Major lessons include: never undervalue the conversion power of clear, emotionally resonant copy or free trials—even for already-free products; prioritize long-term growth and user love over short-term revenue; and treat free users as indispensable, organic engines of word-of-mouth growth.

For further insights and job opportunities at Duolingo, visit their careers page.