EdTech · iOS, Android & Tablets
Language Learning App Development Company
ETREXIO is a software studio based in the United States and Türkiye that designs, builds and operates language learning apps for iOS, Android and tablets, together with the content systems and backends behind them. Two senior builders lead a human-in-the-loop AI workforce, supported by our in-house products DigiSapiens and StackWatch. We built and still operate Learn Languages with Dr. Moku, which has taught Japanese, Korean, Chinese and Arabic to more than 100,000 learners. We have shipped 50+ products, hold a 4.7 rating on Clutch, and our average client stays 5 years. Retainers start at $5,000 per month and cover design, development, deployment and 24/7 operation.
Language learning apps are unforgiving products. They live or die on media playback, retention mechanics and the moments when your learner has no signal, and most development teams treat them like generic apps with videos attached. That is why so many education founders arrive at us with a trail of failed builds behind them: apps locked to a single language because the architecture could not stretch, tablet versions that broke the phone layout, video players that stuttered through the one experience that was supposed to teach.
We build the whole learning system, not just the screens. A language app is a content pipeline first: lessons, courses, audio and video have to flow from your teaching material into the product without a developer touching every update. It is a retention machine second: spaced repetition, progress and streaks have to pull learners back without turning study into a slot machine. And it is a store product third, ranked every day on how it behaves on thousands of devices we will never see.
Post-launch is where our in-house products earn their keep. StackWatch watches crashes, playback errors and API performance around the clock, and fixes flow through the same monthly retainer that built the app. When that loop cut Dr. Moku's already low crash rates further, ratings rose and store rankings climbed visibly across country stores, with signups following. Education apps compound: the team still watching in year five is worth more than the team that shipped in month three.
What we build
A language app is a learning system, not a deck of flashcards.
Content pipelines your teachers can drive.
Admin panels where courses, lessons, video and audio are created, versioned and published without a developer in the loop, so adding a language is an editorial task, not a rebuild.
Spaced repetition and gamification that respect the learner.
Review scheduling, progress, streaks and rewards tuned to bring learners back daily, built as teaching mechanics rather than casino mechanics.
Offline mode, because learning happens in transit.
Learners download lessons on home Wi-Fi and study on subways and planes. The offline feature we built for Dr. Moku lifted sales 36 percent.
Phones and tablets from one codebase.
One Flutter app for iOS and Android, designed responsively for every screen size from day one, so tablet support never breaks the phone experience.
How we approach it
How we take a language learning app from material to the stores, and keep it climbing.
The build is the first few months. The product is the years of learners after. Our process covers both.
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Map the content pipeline before the screens.
We start with your teaching material: how lessons, courses, video and audio are produced, and how they should flow into the app. The admin panel and media infrastructure are designed first, so your team publishes new content and new languages without waiting on developers.
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Design the learning loop, then gamify it honestly.
Spaced repetition scheduling, lesson progression, streaks and progress feedback are designed around how people actually study, in stolen minutes rather than hour-long sessions. Gamification serves retention of knowledge, not just retention of attention.
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Build offline-first, not offline-later.
Download management, local storage and sync are architected in from the start, because retrofitting offline into a streaming-only app is a rebuild in disguise. For language learners commuting through dead zones, offline decides whether the app gets used at all.
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Ship to every screen from one codebase.
One Flutter codebase serves iOS, Android and tablets, with every screen designed responsively from day one. Bob Byrne watched previous teams fail at tablets for years; designed this way, the problem simply ended.
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Operate for the rankings.
Store algorithms rank apps on how they behave: crashes, ratings, retention. StackWatch monitors around the clock, fixes and improvements flow through the retainer, and store listings are tuned continuously. This loop is how Dr. Moku's rankings rose across country stores years after launch.
Real work
Dr. Moku: four failed teams, then a flagship with 100,000+ learners.
Bob Byrne spent 15 years teaching languages through video and mnemonics, and years watching development teams fail him. His fifth app, built with ETREXIO, became the flagship. Five years later we still operate it.
Every language finally in one app.
Previous teams stumbled on video playback, so Bob tested us with a deliberately small job: one video player module. It worked, and the next day he laid out the real project. We unified his scattered single-language apps into one Flutter product where Japanese, Korean, Chinese and Arabic each live as their own course area, run from one admin panel. It has now taught more than 100,000 learners.
The feature that lifted sales 36 percent.
Language learning happens on subways and planes, where signal is missing or data is precious. We built offline mode so learners download lessons on home Wi-Fi and study anywhere, and sales rose 36 percent. On the stability side, StackWatch-driven improvements cut crash rates further and store rankings climbed visibly across country stores, with signups and revenue following.
The failure every other team repeated, ended.
Bob had watched every previous tablet attempt end in fiasco: teams either could not do responsive design or broke the phone experience forcing it onto bigger screens. He asked if tablets were simply impossible. We designed every screen for phones and tablets from day one, the years-long problem ended, and the user pool widened. Five years on, Dr. Moku has never switched teams.
One of the most complex projects that I have ever managed but also one of the easiest because of their attitude, honesty, and resilience. Onwards and upwards.
Questions
What education founders ask about language learning apps.
How much does language learning app development cost with ETREXIO?
Monthly retainers from $5,000, covering design, development, deployment and 24/7 operation of the app, its admin panel and its backend. There is no separate maintenance contract; the same retainer that ships the app keeps it updated and climbing in the stores.
How long does it take to launch a language learning app?
A focused first version typically reaches the stores in 3 to 5 months, including the content pipeline, offline support and store review cycles. The biggest variable is your content: the more structured your teaching material already is, the faster it flows into the product.
We have several single-language apps. Can you unify them into one?
Yes, that is exactly what we did for Dr. Moku, whose earlier teams had left each language locked in its own app. We merged everything into one flagship where each language lives as its own course area, which means one codebase to keep healthy and one brand for the stores to rank.
How do we add new languages or courses without a developer?
Through the admin panel we build alongside the app. Lessons, courses, video and audio are created and published as editorial work, so your linguists and teachers ship content on their own schedule and the app grows without new development cycles.
Do you build spaced repetition and gamification?
Yes, as core mechanics rather than bolt-ons. Review scheduling, progression, streaks and progress feedback are designed around real study behavior, in short daily sessions, and tuned so learners come back for the learning, not just the badge.
Is offline mode really worth the extra build effort?
For Dr. Moku, offline mode lifted sales 36 percent. Language study happens in transit, where signal is missing or data is expensive, so learners download on Wi-Fi and study anywhere. If your users learn in stolen moments, offline is the difference between an installed app and a used one.
Can you support tablets without breaking the phone version?
Yes, if tablets are designed in from the start rather than stretched on later. Previous teams failed Bob Byrne on exactly this for years; we design every screen responsively for both device families from day one, and his tablet problem ended for good.
How do you improve an education app's store ranking?
Stability first, because store algorithms punish crashes before anything else. StackWatch monitoring plus fast fix cycles cut Dr. Moku's crash rates, and ratings and rankings rose visibly across country stores. We pair that with listing optimization and review prompts placed at genuinely happy moments.
Can you take over a language app another team built?
Yes. We audit the code, the content pipeline and the store accounts, stabilize the riskiest parts, put the app under StackWatch monitoring, and continue development from there. Many of our longest relationships, Dr. Moku included, began after other teams had failed. A Clarity Call is the fastest way to find out what your app needs.
Do you keep working on the app after launch?
That is the model. Dr. Moku has been running with us for five years of continuous updates, improvements and fixes, described by its founder as an in-house team that never quits and never slacks. Education products compound over years, and the retainer is built for that horizon.
Client perks
Clients unlock up to $250,000 in tool perks.
Client perks include
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- Airtable
Perk availability depends on provider eligibility at the time of engagement.
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