Systa: System Design Interview

Learn system design by running it. Systa turns distributed systems concepts into live simulators you can break and fix, then gets you ready for the system design interview. Works offline. No account, no ads. Most system design resources hand you a static diagram and hope it sticks. Systa hands you a working system. Read a short lesson, open the simulator and watch a load balancer spread traffic, a cache fill and evict, a message queue back up or a database shard rebalance, all reacting as you turn the dials. Add servers, raise the traffic, trigger a failure and see the trade-off happen instead of imagining it. WHAT'S INSIDE • 103 lessons across 13 courses: Foundations of Distributed Systems, Scaling & Load Balancing, APIs & Communication, Protocols & Wire Formats, Data Storage & Replication, Caching & CDNs, Messaging & Queues, Consistency & Consensus, Architecture & Operations, Cloud & Operations, Reliability & Resilience, Security, and AI & LLM Systems. Step-by-step concept cards with diagrams and quick checks. • 33 interactive simulators: load balancing, caching, rate limiting, message queues, database replication, sharding, consistent hashing, CDN, circuit breaker, API gateway, DNS, TLS, B-tree vs LSM-tree, consensus, autoscaling, backpressure, saga vs 2PC and more. Change the parameters live and watch the system respond. • AI & LLM system design: simulators for tokenization, embeddings, attention, RAG and agents, the topics now showing up in interviews. • 46 case studies with design boards: URL shortener, news feed, chat, photo sharing, video streaming, search autocomplete, notifications, rate limiter and many more. Requirements first, numbers second, high-level design last. • Design playground: drag components onto a canvas, wire them together, run traffic through your own architecture and find the bottleneck before your interviewer does. Export the diagram as an image. • System design interview prep: 88 real interview questions, from warm-ups to hard ones. Answer out loud, then compare against a 30-second answer, a full model answer, trade-offs, follow-ups and red flags. Tick the points you hit; shaky answers come back for review. • Capacity calculators: back-of-the-envelope estimation done right. QPS to server count, storage sizing, bandwidth and egress, cache memory and hit rate. Every number shows its working. • Practice that sticks: quizzes with an explanation for every answer, and spaced-repetition flashcards. • Progress: daily streaks, levels, XP and achievements. WHO IT'S FOR Software engineers and backend developers preparing for a system design interview after the coding rounds or for a senior role, computer science students who want the chapter their degree skipped, and anyone curious how large, scalable systems fit together. Systa turns vague intuition into concrete reasoning: clarify the requirements, estimate the scale, sketch the high-level design (HLD), pick the database, and defend the trade-offs out loud. DESIGNED TO READ WELL A calm, native reading surface you can tune: light and dark mode, accent colours and base tones, serif, sans or mono body text, adjustable text size, and a matching home-screen icon. FREE & PRO Start free: the first lessons, two simulators, two case studies, a flashcard deck, the bandwidth calculator and five playground runs. Pro unlocks everything: all 103 lessons, 33 simulators and 46 case studies, unlimited playground runs, quizzes, flashcards, the 88 interview questions and every capacity calculator. Choose Pro Yearly (US$14.99/year) or Pro Lifetime (US$49.99, one-time). Both restore on any of your devices. Pro Yearly auto-renews unless cancelled at least 24 hours before the period ends. Manage it in your Apple Account settings. Lessons are in English. Terms of Use: https://www.apple.com/legal/internet-services/itunes/dev/stdeula/ Privacy Policy: https://systa.faithdevs.com/privacy