Duolingo Handbook

Issue 110 l Eka’s Weekly Roundup (18 February 2025)

Feb 18, 2025

If you’ve been following this Substack for a while, you’ll know that I have a (very slight 🙈 ) obsession with Duolingo.

So when they published their Duolingo Handbook, I was very excited to dig in and read more about the playbook. We’re huge fans of mobile apps at Eka, having backed Runna, Paired, and most recently Medly.

Read on for our five takeaways 👇

P.S. we had a special guest at our family Christmas dinner …

Five takeaways from the Duolingo Handbook 🗞️

1. Big problems have impact & commercial value

Duolingo’s mission is to make quality education accessible to everyone, tackling a major global challenge especially outside the English speaking world.

I found this slide from GP Bullhound’s latest CCS 2024 report helpful to frame this in a slightly different way.

For us, investing in climate and health means backing companies that address systemic issues and drive large-scale change.

2. Speed, speed, speed

One chapter in the handbook is purely dedicated to speed. Duolingo’s rapid experimentation model — running hundreds of tests weekly under a “V1” mindset helps them create polished, helpful, and intuitive features on-app.

At Eka, we’re laser focussed on speed of execution within consumer applications given the lower barriers to entry compared to other markets & segments.

3. True obsession with customers & their feedback

The one thread throughout the handbook is the team’s obsession with users.

They are nearing 4m reviews on the app store, which is very high. For context, GPT has close to 2m reviews and TikTok is at 18m.

Duolingo continuously refines its platform based on user engagement and feedback. The best impact-driven companies build direct feedback loops with their customers, ensuring their solutions evolve to meet real needs effectively.

4. The power of long view hiring & talent

Duolingo’s uncompromising hiring philosophy ensures every team member is mission-driven and highly skilled.

5. Creativity

What keeps me hooked is 1. the weirdness of the app 2. crazy organic network effects (i.e. my brothers messaging to check if I’ve done my lesson) and 3. a totally unhinged duo on my social media.

A founder last week was telling me about how she was promoting a culture of creativity in her business, and I hadn’t previously realised the importance of this simple but important pillar within consumer-facing applications.

A few caveats around efficacy and obsession

I’ve been doing a lot of thinking about whether the amount of time invested in Duo has paid off for my language skills.

I was speaking to a founder a few months ago who asked whether Duolingo had been truly effective at teaching me German. For context, I now have a 550+ day streak and spend an average of 45m/week on Duolingo. That’s been pretty consistent week on week.

I’m technically at the end of the A2 syllabus and about to go into B1.

Let’s assume I’ve done 5m per day (slightly under 45m weekly average) for my 557 days. That’s about 46 hours on Duolingo.

It looks like A2 is reached after 150-200 hours of study after some Googling/GPT-ing. In London, language courses are pretty expensive so this would have set me back a lot more than the Duolingo subscription price.

For B1 and beyond, I’m considering moving to a hybrid of Duolingo plus another app or language learning website to get ‘properly’ learning. I think the new AI video call feature is going to be helpful for the next leg of fluency but pricing still feels very steep for Duolingo Max.

I’m not planning on breaking my streak anytime soon though, and am still very obsessed with the green owl who joined our family Christmas dinner this year.