Recently, I came across The Duolingo Handbook, a playbook published by Duolingo this year.

As a longtime Duolingo user and fan, I was curious to dive in, and it did not disappoint.

The handbook distills 14 years of hard-earned lessons into five core principles (plus a framework) that have shaped Duolingo into a leader in educational technology.

In this newsletter, I’ll break down the key insights from its 64 pages, making them immediately actionable for anyone looking to build a great company.

And, of course, sharing them here helps me absorb the lessons even better.

#1: Take the Long View

If it helps in the short-term, but hurts in the long-term, it’s not right.

The company’s mission - to make the best education universally available - demands patience and resilience.

For example, while increasing ad frequency could boost short-term revenue, Duolingo limits the number of ads to avoid compromising user retention and trust.

This same principle can be extended to hiring: Duolingo prioritizes exceptional candidates who align with its mission over filling roles quickly, adhering to the mantra: “Better a hole than an a**hole”.

Obviously, not every company can operate like this. Duolingo was fortunate that its founder, Luis von Ahn, had already sold his first company, reCAPTCHA1, so he had the flexibility and perspective to think about Duolingo’s mission first and foremost. They also had the trust of their early investors, and they hired people who were “just as crazy about Duolingo’s mission”.

So while it might not be that easy to sell your company to Google for millions, it might be easier to choose your investors wisely and hire missionaries over mercenaries.

Building a Forever Product

The Duolingo app is designed to be sticky in the short term and transformative in the long-term.

That means that user retention is prioritized, and monetization is carefully balanced to avoid disrupt accessibility.

The freemium model2 eliminates ads and provides unlimited hearts (for mistake tolerance) via subscriptions, while maintaining a robust free tier.

Duolingo is showing that it’s possibile to build a great business while achieving user long-term loyalty.

To do that engineering must require a different approach. At Duolingo they know they are not building systems to last forever, so they test ideas quickly and invest significant engineering resources when something is successful.

For example, When they realized they’d be testing notification copy for years to come, they built a custom tool to allow Product Managers to test copy without engineering support.

And this balance (focusing on speed while reserving long-term investments for what truly works) has guided Duolingo’s success.

#2: Raise the Bar

To change how the world learns, we must do world-class work.

Ownership and Feedback

One key to maintaining high standards is assigning ownership, because “only things that are owned become excellent”.

The standard at Duolingo is “hard on the work, easy on the people”. That means giving constructive and clear feedback that sharpens ideas without undermining relationships (stick to the “what,” not the “who”).

The Bar

Duolingo’s culture demands world-class work across all functions. For product teams, features must meet four criteria:

1. Useful

2. Intuitive3

3. Delightful

4. Polished

Cultural fit is non-negotiable.

The bar for talent is exceptionally high, emphasizing kindness and collaboration alongside skills. A senior executive candidate, with a great CV4, was once rejected for disrespecting a driver.

MVPs no like! V1s are better

This is what the Duolingo team wrote:

The difference is important: MVPs often have a lower standard of quality and can be used as an excuse to ship subpar work.

V1s, on the other hand, are polished.

They may not have all the bells and whistles, but they meet our bar.

Sometimes this approach takes a little longer, but we refuse to compromise our users’ experience by showing them half-baked ideas.

#3: Ship it!

For a good idea to become reality, we need to move with a sense of urgency.

Duolingo’s culture of experimentation drives fast iteration. Weekly app updates and hundreds of simultaneous A/B tests, like optimizing notification copy, enable quick data-informed decisions.

The “clock speed”5 mindset requires people at Duolingo to minimize the time between idea generation, execution, and feedback.

Ruthless Prioritization & Experimentation

At Duolingo, prioritization is sometimes described as “ruthless”: they are decisive about what they focus on as a company, based on what will have the largest impact on their learners.

Letting go of what’s not effective is often as powerful as creating something new.

Some of Duolingo’s best features and campaigns have come from asking ridiculous, unlikely questions.

They are not afraid to experiment, because each experiment, even those that fail, bring the company closer to seeing what works.

#4: Show Don’t Tell (probably my favorite)

We use clear, concise communication that is grounded in data and real impact.

Storytelling is important, but only when data and metrics are at the centre of it.

Metrics, when available, should be at the center of all work and communications. Decisions must be grounded in evidence, not abstract narratives.

By empowering teams to explore bold concepts and letting metrics guide the way, Duolingo ensures that the best ideas rise to the top.

TL;DR

TL;DRs - executive summaries at the top of any important communication - force you to make complex information more digestible, because you have to distill your message down to its most essential points.

The Trust Battery

Building trust is essential. At Duolingo, as it should be everywhere really, trust isn’t assumed, it’s earned. And it’s earned through impactful work.

Each contribution charges the battery, creating a reserve of trust that strengthens collaboration, decision-making, and accountability over time.

#5: Make it Fun

We bring a sense of humor, joy, and imagination to everything we do.

Duolingo is competing with platforms like TikTok, Instagram, and online games for attention, so they have to make learning as fun as any of them.

They are not a game (even though they slowly introduced gamification, which sometimes is not a good thing), but they are not just an education product either.

Absurd sentences (e.g. “Your bear is drinking beer”) and character-driven humor (e.g., Lily’s sarcastic claps) make learning way more engaging.

The Green Machine

The Green Machine is the framework Duolingo uses to put the 5 principles at work. It’s a process of continuous improvement through small changes.

The Green Machine model can help just about any project get on track.

Below the six steps:

1. Staff It with Great People: Lean and scrappy teams of exceptional talent.

2. Define Success: Metrics or qualitative goals guide iterations and success.

3. Set Guardrails and Think Long-Term: Long-term thinking ensures sustainability.

4. Build the Thing and Set Up Feedback Loops: Just start building, and create the right continuous feedback loops.

5. Execute with Urgency and Excellence: Leverage the compound nature of small improvements. Move fast.

6. Double Down on What Works, Stop What Doesn’t: Successful features receive resources, what is not working is cut.

Hope you enjoyed this.

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• The Best of Naval at the Joe Rogan podcast

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• I tried grayscale mode for 7 days on my phone

See you all next Sunday 🗓️
Thanks,
Giacomo