Staff Interview Questions at General

Design a system that detects fraudulent credit card transactions in real-time (decision in under 50ms). The system processes 10,000 transactions per second.

Your team is two days before launch. A junior developer finds a critical security vulnerability in the payment flow. Fixing it will delay launch by a week. Your manager says 'we'll fix it after launch.' What do you do?

Design a pipeline to detect fraudulent transactions in near-real-time. Transactions arrive at 10,000/second. Your ML model takes 5ms to evaluate one transaction.

Design a data architecture on AWS for a startup that needs to: store raw events, run real-time analytics, run daily batch reports, and serve an API with sub-10ms response time.

Your team wants to add server-side rendering to an existing client-side React app. What are the actual technical challenges beyond 'just use Next.js'?

Explain Module Federation in React micro-frontends. What are the main production challenges?

You're building a micro-frontend architecture where 5 teams ship independent React apps that compose into one shell. How do you handle shared state, shared dependencies (avoid duplicate React), and routing?

Design a schema to support a multi-tenant SaaS application where each tenant has its own isolated data. Compare row-level isolation, schema-per-tenant, and database-per-tenant. When would you choose each?

Design a data lake architecture on AWS that ingests both real-time streams and batch uploads, makes data queryable within 5 minutes, and costs less than $10K/month for 100TB.