Duolingo Virality and Habit Design

Albert Cheng has led growth at three of the world’s most successful consumer subscription companies: Duolingo, Grammarly, and Chess.com. A former Google product manager (and serious pianist!), Albert developed a unique approach to finding and scaling growth opportunities through rapid experimentation and deep user psychology. His teams run 1,000 experiments a year, discovering counterintuitive insights that have driven tens of millions in revenue.

What you’ll learn:

1. How to use the explore-exploit framework to find new growth opportunities

2. How showing premium features to free users doubled Grammarly’s upgrades to paid plans

3. What good retention looks like for a consumer subscription app

4. Why resurrected users drive 80% of mature product growth

5. Why “reverse trials” work better than time-based trials

6. The three pillars of successful gamification: core loop, metagame, and profile

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Brought to you by:

Vanta—Automate compliance. Simplify security.

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Where to find Albert Cheng:

• X: https://x.com/albertc248

• LinkedIn: https://www.linkedin.com/in/albertcheng1/

• Chess.com: https://www.chess.com/member/Goniners

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Where to find Lenny:

• Newsletter: https://www.lennysnewsletter.com

• X: https://twitter.com/lennysan

• LinkedIn: https://www.linkedin.com/in/lennyrachitsky/

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Referenced:

• How Duolingo reignited user growth: https://www.lennysnewsletter.com/p/how-duolingo-reignited-user-growth

• Inside ChatGPT: The fastest-growing product in history | Nick Turley (Head of ChatGPT at OpenAI): https://www.lennysnewsletter.com/p/inside-chatgpt-nick-turley

• Explore vs. Exploit: https://brianbalfour.com/quick-takes/explore-vs-exploit

• Grammarly: https://www.grammarly.com/

• Reforge: https://www.reforge.com/

• Chess.com: https://www.chess.com/

• Everyone’s an engineer now: Inside v0’s mission to create a hundred million builders | Guillermo Rauch (founder & CEO of Vercel, creators of v0 and Next.js): https://www.lennysnewsletter.com/p/everyones-an-engineer-now-guillermo-rauch

• Building Lovable: $10M ARR in 60 days with 15 people | Anton Osika (CEO and co-founder): https://www.lennysnewsletter.com/p/building-lovable-anton-osika

• Figma: https://www.figma.com/

• Cursor: https://cursor.com/

• The rise of Cursor: The $300M ARR AI tool that engineers can’t stop using | Michael Truell (co-founder and CEO): https://www.lennysnewsletter.com/p/the-rise-of-cursor-michael-truell

• Claude Code: https://www.anthropic.com/claude-code

• GitHub Copilot: https://github.com/features/copilot

• Noam Lovinsky on LinkedIn: https://www.linkedin.com/in/noaml/

• The happiness and pain of product management | Noam Lovinsky (Grammarly, Facebook, YouTube, Thumbtack): https://www.lennysnewsletter.com/p/the-happiness-and-pain-of-product

• Kyla Siedband on LinkedIn: https://www.linkedin.com/in/kylasiedband/

• The Duolingo handbook: https://blog.duolingo.com/handbook/

• Lenny’s post on X about the Duolingo handbook: https://x.com/lennysan/status/1889008405584683091

• The rituals of great teams | Shishir Mehrotra of Coda, YouTube, Microsoft: https://www.lennysnewsletter.com/p/the-rituals-of-great-teams-shishir

• Duolingo on TikTok: https://www.tiktok.com/@duolingo

• Kasparov vs. Deep Blue | The Match That Changed History: https://www.chess.com/article/view/deep-blue-kasparov-chess

• Magnus Carlsen: https://en.wikipedia.org/wiki/Magnus_Carlsen

• Elo rating system: https://www.chess.com/terms/elo-rating-chess

• Stockfish: https://en.wikipedia.org/wiki/Stockfish_(chess)

• AlphaGo on Prime Video: https://www.primevideo.com/detail/AlphaGo/0KNQHKKDAOE8OCYKQS9WSSDYN0

• Statsig: https://www.statsig.com/

• The State of Product in 2026: Navigating Change, Challenge, and Opportunity: https://www.atlassian.com/blog/announcements/state-of-product-2026

• Erik Allebest on LinkedIn: https://www.linkedin.com/in/erikallebest/

• Daniel Rensch on X: https://x.com/danielrensch

• Chariot: https://en.wikipedia.org/wiki/Chariot_(company)

• San Francisco 49ers: https://www.49ers.com/

• Breville Barista Express: https://www.breville.com/en-us/product/bes870

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Recommended books:

• Snuggle Puppy!: A Little Love Song: https://www.amazon.com/Snuggle-Puppy-Little-Boynton-Board/dp/1665924985

• Ogilvy on Advertising: https://www.amazon.com/Ogilvy-Advertising-David/dp/039472903X

• Dark Squares: How Chess Saved My Life: https://www.amazon.com/Dark-Squares-Chess-Saved-Life/dp/1541703286

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Production and marketing by https://penname.co/. For inquiries about sponsoring the podcast, email podcast@lennyrachitsky.com.

Lenny may be an investor in the companies discussed.