Duolingo Engineering: Karin Tsai on Opinionated Development

Duolingo's Engineering Director Discusses Development and Culture

Karin Tsai began her tenure at Duolingo in 2012 and currently holds the position of Director of Engineering.

Recently, she participated in a discussion at TechCrunch’s City Spotlight: Pittsburgh, detailing the company’s comprehensive development procedures and distinctive corporate culture.

Timing of the Interview

The interview was recorded in advance and broadcast the day following Duolingo’s submission of its SEC Form S-1 in preparation for its initial public offering (IPO).

Due to SEC regulations enforcing a quiet period, this interview represents potentially the final public statement from the company for an extended duration, as stated by Tsai.

Part of a Larger Series

This conversation is the newest installment in TechCrunch’s in-depth exploration of Duolingo’s presence in Pittsburgh.

Previously, a four-part series was released last month, covering the company’s beginnings, its product-led growth strategy, its approach to monetization, and the methods used to develop and launch new features and initiatives.

The series provides a comprehensive overview of Duolingo’s operations and evolution.

The Foundation: A/B Testing at Duolingo

Tsai collaborates with Duolingo’s approximately 170 engineers, representing the bulk of the company’s workforce. This engineering-focused structure has established A/B testing as a central tenet of Duolingo’s operational strategy.

The goal is to develop an application that delivers both effective learning and inclusive gamification. Currently, around 100 distinct A/B tests are frequently in progress, prompting Duolingo’s analytics division to create a dedicated dashboard for monitoring experimental outcomes.

Initial Insights from Early Testing

During the Duolingo EC-1 phase, a notable pattern emerged: the product team consistently initiates A/B tests for new features within the French course, specifically targeting English speakers. This isn't due to a preference for the French language.

Rather, the French course’s substantial popularity provides a more statistically sound environment for initial testing before broader implementation across other languages. Testing in less-trafficked courses, such as Hindi for English speakers, would require a significantly extended timeframe to yield meaningful data.

Prioritizing User Experience Over Revenue

A particularly memorable A/B experiment for Tsai centered on the subscription page, and involved a decision to forgo potential revenue gains.

This highlights Duolingo’s commitment to product-led growth, a key factor in the app’s success as the most downloaded edtech application.
The experiment also raises questions about the ethics of A/B testing.
It's worth noting that Apple is also introducing A/B testing and in-app event tracking to its App Store.

The Evolution of Duolingo's Monetization Strategy

Initially, Duolingo debuted with a firm commitment to a revenue model devoid of advertisements, subscriptions, or in-app purchases. However, the platform now incorporates all three. Despite its current financial success, the decision to introduce charges was a complex one, seemingly at odds with Duolingo’s core mission of accessible, free education.

Luisa Tsai, observing the company’s expansion from a team of 15 to over 400, detailed how the leadership navigated this internal conflict and eventually implemented a system to generate revenue from a portion of its user base – approximately 5%.

Key Insights from Duolingo’s S-1 Filing

Duolingo’s S-1 filing reveals substantial growth, successful monetization strategies, and a renewed emphasis on English certification.
The company’s journey demonstrates a skillful adaptation to the demands of sustainable business practices.

The shift towards monetization wasn't simply a financial necessity; it represented a strategic evolution. Duolingo needed to secure its long-term viability while upholding its educational goals.

This involved carefully balancing the desire to remain free for the majority of users with the need to invest in platform improvements and expand its offerings. The introduction of a subscription model and targeted advertising allowed for this balance.

Monetization became a key component of Duolingo’s strategy, enabling continued innovation and broader accessibility to language learning resources. The company’s success highlights the challenges and opportunities inherent in scaling a free educational platform.

Fostering Constructive Debate Within a Startup Environment

The distinctive company culture referenced by Tsai underwent a significant evolution during the pandemic. This coincided with Duolingo’s transition, alongside numerous other tech firms, to a distributed work model.

A key question arose regarding whether remote work arrangements might hinder productive debate and disagreement. This applies to decisions ranging from minor A/B tests to substantial opportunities concerning monetization strategies.

Tsai highlighted the impact of a weekly communication from co-founder Luis von Ahn. This email, coupled with a commitment to transparency regarding failures, proved instrumental in maintaining open dialogue.

The Importance of Opinionated Companies

Our discussion then shifted to the role of strong opinions within a company. From its inception, Duolingo has operated as an opinionated organization. This is evident in choices regarding its location, funding levels, and monetization approaches – all designed to establish a clear differentiation from its competitors.

However, cultivating such an environment is not without its challenges, particularly in a world characterized by increasing polarization.