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Based on Lenny's Podcast data
Lenny's Knowledge Sketch

The A-Side & B-Side:
Building Duolingo to 200M Users

Gina Gotthilf
Co-founder & COO, Latitude
Former Head of Growth, Duolingo
2024
Philosophy

Every Life Has An A-Side & B-Side

AHIGHLIGHTSBTHE REST
"Most of us have a lot of B-moments every day, every week, every month. It's easy to think things aren't going to work out for us because we're in one of those B-moments, if we don't recognize them as moments."
  • Your A-side is what you show the world: the wins, the Instagrammable highlights
  • Your B-side is where the real work happens: the failures, pivots, and persistence
  • Both are essential. Recognizing B-moments as temporary is key to resilience
  • Career is long. You have time to figure it out. Don't stress the pace
The Duolingo Playbook

How Brand + Product = Viral Growth

MISSIONLOVABLE BRANDWORD-OF-MOUTHORGANIC GROWTHPR & MEDIACOVERAGE
200M
monthly active users
3M
starting users
66x
growth from mission
  • Mission first: "Free language education for the world" is bigger than "download an app"
  • Brand voice: Playful, unexpected, quirky—never generic. The owl has personality.
  • One post a week: Share data proving effectiveness. Make the mission visible in every channel
  • Testing everything: A/B tested sad owl's tears, notification copy, paywall messaging
  • PR is organic: A lovable brand gets reporters to write stories without you asking
Gina's insightCommunication isn't about conveying a message. It's about conveying it so the listener receives it, understands it, and remembers it.
Organic Growth

What Actually Works (Without Paid)

  • Product-led growth: A/B testing and data science are organic growth. They're free growth channels.
  • Copywriting matters: Test your paywall message. "By paying, you make language accessible to millions" moved the needle.
  • Brand cohesion: Every notification, email, screen should feel like Duolingo. Could another company write this? If yes, rewrite it.
  • Mission in product: The mission of accessibility affects conversion rates. People pay for the mission, not just the feature.
Failed test

Posting team photos on Facebook with "behind the scenes" captions. No one cared. Lesson: Don't confuse internal stories with external resonance.

Passive-aggressive genius

The "This doesn't seem to be working" notification after 5 days of inactivity became a meme. It's Duolingo's voice and it drives retention.

Voice & Copy

Build a Unique Voice

  • Ask of every piece of copy: "Could this be written by another company?"
  • If yes, rewrite it until it can't be.
  • Define the voice explicitly: tone, words, what's too much, what's too little
  • Hire for brand fit. New hires won't naturally write in your style—train them
  • Quirk + humor + self-deprecation = people feel it, share it, remember it
The owl effectPersonality in product is a growth lever. Duolingo's tone of voice became its most defensible asset and its strongest acquisition channel.
Contrarian

Growth Myths (That Are Wrong)

You need a huge paid budget to grow fastINSTEAD →Organic + brand + product > paid. Duolingo grew 200M users mostly without paid ads.
Brand is a luxury, growth is coreINSTEAD →Brand IS growth. A lovable brand multiplies everything: retention, referrals, PR.
PR and marketing are nice-to-havesINSTEAD →PR is the highest-leverage channel. A good story beats paid ads 100x over.
Failure means you're on the wrong pathINSTEAD →Your B-side is where the learning lives. Recognize it as a phase, not an ending.
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