Design Lingo: System Design

Team inspire

About this app

Preparing for an SDE interview and freezing the moment someone says "design a rate limiter"?

Design Lingo turns low-level design and system design into short, playable lessons — the way Duolingo teaches languages. Five minutes on your commute is enough to build real intuition, not memorised answers.

BUILT FOR INTERVIEW ROUNDS
Every lesson is framed the way interviewers actually ask. Concurrency, caching, sharding, message queues, consistency, rate limiting, API design — explained through the exact scenarios that come up in LLD and HLD rounds at product companies.

HOW IT WORKS
• Learn a concept in a 3-minute lesson, in plain language
• Apply it immediately in an interactive quiz
• Read the "Interview Pro Tip" that tells you how to say it out loud in a real round
• Keep your streak going and watch your XP climb

KEY FEATURES
• Bite-sized lessons — real progress in a few minutes a day
• Interactive quizzes — active recall beats re-reading notes
• Structured learning path — concurrency, synchronisation, async, in the right order
• Progress tracking — XP, streaks and a leaderboard to keep you honest
• Offline-friendly — download lessons and study on the metro
• Dark mode — built for late-night prep

WHAT YOU'LL COVER
Thread safety and race conditions. Producer-consumer and semaphores. Event loops, promises and non-blocking I/O. Caching strategies. Load balancing. Database sharding and replication. CAP theorem. Rate limiting. Idempotency. Designing for scale.

WHO IT'S FOR
• Engineers with an interview in the next few weeks
• Students and new grads preparing for campus and off-campus SDE roles
• Working developers who want to stop nodding along in design reviews

No 40-minute videos. No 300-page PDFs. Open the app, learn one thing, close it.

Start your first lesson today.