January 25, 2021

How To Build An App Like Duolingo

Duolingo came on the scene in 2011, operating as a teach-and-translate language learning app. It has since transformed into a $700+ million business and become the first EdTech app to top $140 Million in annual revenue.   

Pretty good numbers for a language-learning app that still doesn't need to charge its users a penny and went several long years without any revenue. 

It's a good time to be investing in EdTech app development. Research shows that the impact of COVID-19 has led to a 335% increase in revenue  — but few entrepreneurs know what it takes to build a competitive EdTech platform.

Believe me; we always see these when solo founders throw in the towel and start calling agencies. So, with these promising figures and the technology at your disposal, don’t be the person who skipped over AI-powered technology, potentially equalling, if not replacing, human educators.

This guide breaks down the technology used for Duolingo, the components needed to compete in the market, and a ballpark on how much each part costs. Be sure to check out the competitor analysis at the end to see where your app would fit in the competitive landscape.

What The Duolingo App Does

Duolingo operates as an augmented reality app embedded with a multilingual chatbot boasting speech recognition capabilities. This 24/7 virtual language learning assistant provides interactive sessions to millions of learners worldwide in nearly 40 languages.

These trending technologies play a critical role in everything the Duolingo app does. Equally as impressive is the machine learning technology embedded in the app, which allows it to also learn from its users while teaching them.

The app achieves this by ensuring its content is rigorously checked and tested by its AI-based algorithms and by seeking verification from its learners. It does this by selecting the answers offered by most users and constantly updating its knowledge base of languages. 

The language and logistics behind the Duolingo app provide an interactive experience to its users where they can translate words, phrases, and sentences to their chosen language of learning from their native tongue. 

The app isn’t just the driving force behind the Duolingo platform. The website is also stacked with its own family of software and algorithms providing innovative learning features to the Duolingo community. 

Can You Build an App Like Duolingo?

So, is it possible to clone the language learning app described by TIME Magazine as ‘holding the secret to the future of education? Is it realistic to compete with the education app currently boasting a 4.5-star rating from over 10 million users?  

While it is doable, there are important factors to consider, most notably tech and budget-related. For example, how do you build a tech stack capable of instantly translating the world’s predominant languages into one another?

Do you have the tech resources to maintain a multilingual chatbot with machine-learning capabilities to teach and learn from its users? This type of voice-recognition technology is still at an early stage and will require the services of experienced developers to incorporate it into your build. 

Voice recognition technology
Voice recognition technology

Let’s not forget about the multiple language requirements. Do you have the access and finances to work with leading language experts? If so, what about the software and algorithms needed for storing and analyzing this complex language data?

This type of immersive learning experience could replace traditional forms of education, as AI-powered learning technology can potentially replace human teachers. 

EdTech apps like Duolingo are learning to utilize these trending technologies to pierce through the education industry like never before. Let’s look at what’s needed to bring this language-learning app to the market.

Language Learning App Features

To build a Duolingo-clone app, you must overcome specific technical challenges to ensure the following core features are embedded in your language-learning app.

User Profiles

This feature is needed for user onboarding and registration and will need to include the option to sign up via Google and social media accounts. This feature will consist of personal information as well as privacy settings.

Language Courses & Levels

These features will test a user's language level and standard to provide them with suitable courses and goals to hit. It should also include personalization elements allowing users to plan their unique learning path.

Practice Sessions & Revisions

This feature is needed for monitoring and tracking a user’s process & performance. It can include a history of activities, achievements, and punishments, such as the Duolingo ‘Hearts Feature’. This part of the build should also include speaking & listening exercises and translating options.

Gamification + Animation

While gamification is not a requirement, Duolingo’s gamified approach adds fun to learning and makes the process more stimulating for its users. A language learning app will need sound effects and animation to function accordingly.

Push Notifications 

As with any app, push notifications help increase conversions and retain users. It is a key feature for any language learning app. Duolingo has made great use of this by using its push notification mechanisms for reminders and tracking through insistent daily commands. It also provides a learning structure that helps users stay on track. 


Again, a partial requirement, but there are benefits to having a community of learners interacting with one another via your app. Duolingo originally had a ‘Club’s feature,’ which they then developed into a ‘Leaderboard’ feature. This was aimed at encouraging the Duo community to hold conversations centered around their current standings. Users can also compete with one another by completing courses.

Chatbot w/ Voice Recognition 

An absolute necessity for a functioning language learning app is a 24/7 multilingual chatbot embedded with speech recognition capabilities. As mentioned, this is not just for teaching purposes but also for improving the app's performance via machine learning. 

Chatbot feature
Chatbot feature

While a chatbot is one of the trickiest features to integrate, this type of AI-powered technology has unlimited potential in the EdTech industry. Google’s Cloud Natural Language API is a natural language technology developers can use to incorporate this feature into a language learning app.

Language Learning App Tech Stack

To successfully build a fully functioning language learning app, you will need an understanding of the different layers of the technology behind such a build.

The tech stack refers to the combination of different technologies built on top of each other, flowing up and down the stack. Keep in mind that the stack behind major apps like Duolingo is constantly evolving to keep up with trends and technical debt.

The following is an overview of the type of tech stack required for a language-learning app:

Development Functionality Tech Stack
Frontend Downloading apps
Layout of components
Resides on app’s device
Visual & interactive elements
Java, JS,
Backend Storage & analytics
Access data via API
Runs behind the scenes
AngularJS, React.js, Kotlin,
Scala, Ruby, JavaScript,
Python, Django, Vue.js
Native Programming language for specific platforms Java, Kotlin, Scala,
Objective-C, Swift

Voice recognition
Push notifications
Artificial intelligence
Design + wireframes
Layouts + transitions
Speed + functionality
On-site data storage Cassandra, MongoDB,
MySQL, Postgres, HBase
Analytics Data analysis Apache, Spark, IBM, Hadoop
Cloud Storage Off-site data storage
Manages back-end capabilities
Google Cloud,
Amazon Web Services (AWS)
Android Apps Android programming language Java
iOS APPs iOS programming language Swift

Duolingo’s Original Tech Stack

Even in 2011, Duolingo was making technological advances by incorporating a type of machine learning to aid in developing its product. As well as teaching, the app ran tests to determine how quickly users were learning languages and how they could update their platform to provide a more efficient learning experience. 

From the early days, Duolingo ran on Amazon Web Services and used SQL and DynamoDB to store data and use vocabulary. The backend was written in Python, whereas the frontend consisted of backbone.js, jQuery, and Twitter Bootstrap. Fast forward to 2021, and many new languages and tools have been added to this build.

The following table displays the current tech stack being utilized by the Duolingo tech team:

Application & Data Utilities DevOps Business Tools
Amazon Cloudfront & Amazon S3 Google Tag Manager & Google Analytics New Relic Google Fonts
Javascript & Objective-C Amazon SES Webpack Zendesk
Modernizr & CloudFlare GitHub Pages Varnish G Suite
Bootstrap & MathJax Mixpanel Rollbar Gmail
Ubuntu, NGINX, Fastly JQuery Shopify

Duolingo Website

Behind every fully functioning app is a website actively using many different technologies, holding everything together. A website also serves as a base and online presence for customer sign-up, marketing, advertising, and more.

Duolingo website
Duolingo website

The Duolingo website is built on the WordPress management system and uses 67 active technologies. These include Apache, LetsEncrypt, HTML5, webpack, Google Analytics, and Google Font API.

The Duolingo website has over 45 million monthly visitors, with 25% of the traffic generated in the United States. This volume of traffic ranks Duolingo’s website at number 1,060 globally.

How Much Does it Cost To Build an App Like Duolingo?

Now that you know the technology and features needed to build a language-learning app, let's consider the potential costs of bringing your app idea to life.

Hiring a custom software developer is best if you need more tech resources. This app development phase is not cheap, and the overall cost is generally determined by a developer’s location, reputation, and hourly rate. 

The following factors will determine what you end up spending here:

  • Number of hours to design UI/UX
  • Number of hours to develop app platform
  • Number of hours to develop backend servers 
  • App developer's hourly rate

While more cost-effective nearshore options are available, the average hourly rate for the top U.S. tech hub cities (SF, LA, NYC) is generally between $100 - $199 per hour. The minimum project size requirements for SF and LA start at $10,000, whereas New York City is closer to $50,000.

IT staff augmentation is better if you have tech resources at your disposal but need technical expertise and guidance. Plenty of U.S. tech companies are utilizing IT staff augmentation to build apps at a lower cost-effectively

The time and budget requirements for every app differ as it depends on the scope and complexity of the app, as well as the number of developers needed. But to give you an idea, the following is a broad example of Rootstrap’s app development approach used by MasterClass, Google, Tony Robbins, etc.

Project Phase Tasks Time Cost

Market capitalization
User demographics
App idea validation
Market research
Story mapping

1-2 weeks


App Scoping & Analysis
App category
App complexity

1-2 weeks


Design & Development
Data Storage
UI/UX Design
Design assets

12 - 16 weeks


Deployment & Warranty Period


1-4 weeks


Post-launch Maintenance
Design changes
App Updates
Bug fixes



Business Model & Strategy

While this guide provides a technical overview of a language learning app, this will only work with a solid business strategy for your language learning app idea.

Now that you have an idea for the technology behind a language learning app, you will need to put a plan to generate a return on investment from your app idea.

This may take time, as evident from Duolingo going several years without enjoying any revenue. Unlike the development of an Uber-like app where a freemium service is not an option, monetization is necessary to make a profit when building an app like Duolingo.

Let’s take a look at how you can utilize monetization to generate a profit from your language learning app.


There are four proven ways to make money from a language learning app. Let's take a look at each.

Freemium (Free Subscription):

Users can download the app for free and upgrade to premium membership. 

Paid Subscription:

Users avail of paid membership after downloading the app. A free trial is also a popular option. Duolingo Plus offers a 14-day free trial before adopting a $6.99 monthly charge, allowing offline learning. 

In-app Purchases:

Duolingo capitalizes on this by selling its virtual currency Lingot. This currency allows users to buy features such as bonus skills and power-ups from the Duolingo shop

In-app Advertising:

Duolingo uses in-app advertising to promote its paid subscription and available purchases between classes.

Language Learning App Competition

While Duolingo currently offers the highest number of languages in the market, it has some strong competitors, notably Rosetta Stone.

We touched on the importance of market research and knowing what the competition is up to; it’s equally important to know the type of tech stacks they are incorporating into their builds, as this will be behind any new innovative features they provide. 

A good example of this is a new language-learning app on the market called LanguageChat. The app combines Google’s Cloud Natural Language API, Microsoft's Azure, and Amazon Web Services (AWS) to let users produce original content on their topics of interest. 

Mondly is another prime example of a competitor utilizing technology such as virtual reality to stay ahead of the game. Mondly was the first to produce a language-learning VR app with a built-in chatbot embedded with speech recognition for over thirty languages.

Let's take a look at some of the most popular language-learning apps on the market:





Business Model





Mondly 33 2017 20+ mill Subscription
14 2007 10+ mill



25+ mill

LingoDeer 10 2017 10+ mill
LinQ 24
Memrise 25 2010 35 +mill

(w/ Disney)



30+ mill




60+ million

100+ million


What To Take Away

Since the inception of Duolingo, the technology behind education apps has developed rapidly. Factor in the impact of COVID-19 on the education sector, and it’s no wonder investment portfolios are stacked with the latest and greatest EdTech stocks.

Duolingo effectively utilizes augmented and virtual reality technologies to improve everyday language immersion. With a product offering so much potential and the technology at your disposal, you could be the founder of the latest innovative EdTech app to hit the Google Play and App stores.

While voice technology is still immature, it is arguably the feature with the greatest potential to spearhead us into the new world of tech-powered education. The real-time translation of Duolingo-like chatbots is changing the traditional approach to learning a new language.

To stay one step ahead of the game, it's important to embrace and take advantage of the latest technological advancements at your disposal. The combination of learning and gamification has done just this for Duolingo.

Frequently Asked Questions

How to create an app like Duolingo

To create an app like Duolingo, you will need features such as voice recognition, sound effects, push notifications, and a multilingual chatbot. Duolingo used machine learning and artificial intelligence to create these features. See how you can use IT staff augmentation to build a Duolingo-like app.

What languages can you learn in Duolingo?

Duolingo currently has 36 languages to choose from. Some of the most popular courses available are English for Spanish speakers and vice versa, French, German, and Japanese for English speakers, as well as English for Russian speakers.  

What software was used to develop the Duolingo app?

The Duolingo app was built on Amazon Web Services, Python was used for the backend development, and jQuery, backbone.js, and Bootstrap were used for the front-end experience. The Duolingo app is currently operating with 23 different technologies. See why U.S. tech companies choose IT staff augmentation to build EdTech apps like Duolingo.

How to build a Duolingo clone

To build a Duolingo clone, you will need to use trending technologies such as machine learning, artificial intelligence, and augmented reality. Your Duolingo clone will need embedded features such as a multilingual chatbot, push notifications, and speech recognition. See how IT staff augmentation can help you build a Duolingo clone.


Shaun Kennedy

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