Kaitenji - Japanese Learning Platform
Client
Greg Stoll
Category
Language Learning SaaS (Web App)
Duration
8 months
Location
Olathe, KA
Tech Stack
Frontend: React
Backend: Node.js
Search: Elasticsearch
Hosting & Infrastructure: [Confidential, client-specific]
About the Client
Kaitenji is a Japanese language learning platform built over the course of ~8 months using Node.js and React. Designed for learners of all levels, it provides a comprehensive suite of study tools, from vocabulary and kanji practice to grammar and Japanese name exploration. The platform is powered by Elasticsearch for fast and accurate dictionary search and offers an efficient study experience through advanced learning algorithms.
The Challenge
The client needed to bring to life a comprehensive Japanese learning platform that could compete with established apps while offering unique features for serious learners. The main challenges included:
Complex Data & Search Requirements — Supporting fast, reliable English–Japanese dictionary lookups across thousands of entries, requiring a robust search engine.
Advanced Learning Mechanics — Implementing a quiz system with Spaced Repetition (SRS) to optimize memory retention, demanding careful algorithm design.
Highly Interactive Experience — Delivering responsive study tools (for vocab, kanji, grammar, and more) in a single, seamless web interface.
Scalable Personalization — Allowing users to create custom decks and study paths without compromising performance.
Text Parsing Innovation — Building the ability to ingest entire Japanese novels or long text blocks and automatically extract vocab and kanji — a feature rarely seen in competitors and technically complex to implement.
End-to-End Development Partnership — The founder required a development team that could own the full product build (frontend, backend, and infrastructure) while also collaborating on ideas, adapting quickly, and ensuring high quality throughout the 8-month timeline.
Key Goals
We developed a highly interactive web application that enables users to:
Search the English–Japanese dictionary with Elasticsearch for instant results.
Study vocabulary, kanji, grammar, Japanese names, and other dictionary entries individually.
Use a quiz system powered by an SRS (Spaced Repetition System) algorithm, optimizing study sessions for memory retention.
Create and manage custom decks to personalize their study experience.
Parse entire Japanese novels or large text blocks, automatically extracting all vocabularies and kanjis for targeted review — a technically complex feature that significantly boosts learning efficiency.
Our Approach
Radical Online approached Kaitenji as both a technical challenge and an educational mission, blending engineering precision with a learner-first mindset. Our strategy focused on:
Immersive Product Discovery — We studied the workflows of language learners and even learned the basics of Japanese ourselves, ensuring features aligned with real study habits.
Engineering for Speed & Accuracy — We selected Elasticsearch early to guarantee instant dictionary lookups and scalable performance across thousands of entries.
Learning Science at the Core — The SRS quiz system was carefully implemented to maximize retention, blending proven cognitive science principles with a smooth user experience.
Iterative Feature Development — We prioritized high-value features (dictionary, quizzes, custom decks) and layered on advanced capabilities like text parsing for novels, testing each increment with real users.
Collaborative Agility — Working closely with the founder, we adapted rapidly to evolving ideas, provided technical recommendations, and ensured continuous delivery throughout the 8-month build.
Focus on Differentiation — The novel parsing tool became a signature feature, setting Kaitenji apart from competitors by enabling learners to study from authentic Japanese texts.
Through this approach, we delivered a scalable, technically advanced, and learner-centric SaaS that exceeded client expectations and positioned Kaitenji as a standout tool for Japanese language learners worldwide.
Key Features
Advanced Search with Elasticsearch: Instant, accurate dictionary lookups with support for English-to-Japanese queries.
Multi-Category Study Content: Vocabulary, kanji, grammar points, Japanese names, and more, all in one platform.
Custom Decks: Flexible study lists users can create, edit, and manage themselves.
SRS-Driven Quizzes: Automated review scheduling based on proven spaced repetition methods.
Text Parsing for Vocabulary Extraction: Upload or paste Japanese text (even full novels) to extract relevant vocab and kanji for future study.
SRS-Driven Quizzes: Automated review scheduling based on proven spaced repetition methods.
Impact
Platform launched successfully and is live with 1,200+ registered users.
Over 1,000 users have completed reviews using the quiz system.
Delivered a technically complex platform that met and exceeded client expectations.
What our client said
"Radical Online partnered with us for over a year to develop a Japanese language learning SaaS web application. The team demonstrated exceptional talent, dedication, and adaptability, even taking the time to learn the basics of a complex language to ensure the product’s success. They overcame many challenges, brought fresh ideas, and turned our vision into a high-quality app. We look forward to continuing our collaboration in the future."
Greg Stoll
Revenue Analyst at LifePoint Health
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