Design Slack (MVP): Frequently Asked at OpenAI, Meta & Databricks (Walkthrough)

Description

This is a full system design walkthrough for one of the most common interview questions at top tech companies: Design Slack. I walk through every phase of the answer — scoping requirements, high-level architecture, API and database schema design, real-time delivery with WebSockets, and deep dives into the message write path, eventing reliability, and data modelling. This is the level of depth interviewers expect at Staff and Senior engineer level. This question appears frequently in the OpenAI system design interview, the Coinbase system design interview, and the Databricks system design interview. The same core problem — designing a real-time messaging platform — also shows up in the Meta system design interview and at Google, Amazon, and Microsoft What I cover: — Scoping a 2-week MVP under interview time pressure — Event-driven microservices architecture — PostgreSQL schema design with indexes for chat timelines and threads — WebSockets vs SSE vs polling for real-time messaging — Redis Pub/Sub as an event bus and when to upgrade to Kafka — JWT authentication and API Gateway design — Pre-signed URL file uploads to object storage — The outbox pattern for reliable event delivery — Cursor-based pagination for message history — Notification pipeline and thread follower derivation — Idempotency and database-level deduplication under concurrent retries — How the system degrades gracefully under partial failure If you're preparing for system design interviews at OpenAI, Coinbase, Databricks, Meta, Google, Amazon, Microsoft, Stripe, or anywhere that asks about real-time messaging or chat, this walkthrough gives you a reusable framework. Need mock interview help? Book coaching → https://www.coditioning.com/mockinterview/human Coditioning platform: https://www.coditioning.com/ 📌 Check out coditioning.com for mock interviews, coaching, and AI-powered prep tools tailored for software engineers. Get access to mock interviews (human & AI) and other interview prep resources, including: ✔️ Diagnostic tests to identify knowledge gaps ✔️ Custom learning paths with an AI coach ✔️ Crash courses in LLD, System Design, & Coding ✔️ And more resources to help you ace your SWE interviews 👩‍💻 Join the Coditioning Community: Discord: https://discord.gg/eNYYvpRyBt ✅ Subscribe for More Insightful Content: *Don't forget to like, comment, and subscribe* if you found this video helpful — and good luck in your interviews! *What is Coditioning?* *Coditioning is your go-to platform for getting truly interview-ready by optimizing your chances of landing offers at your target companies.* While we specialize in helping candidates break into AI-startups and FAANG+ companies like *Amazon, Meta, Google, Microsoft, Netflix, and Reddit* , our tools and strategies apply across the tech industry. We offer mock interviews (human & AI), personalized feedback, and learning resources covering coding, system design, production engineering, behavioral interviews, and more — all designed to help you succeed. 👉 coditioning.com: https://www.coditioning.com #systemdesign #openai #databricks #coinbase #systemdesigninterviewprep #faangprep #techinterviewprep