← Grammarly Interview Insights
Seen this one floating around on forums so I wasn't totally blind going in, but the Excalidraw tool was new to me and I spent the first few minutes just figuring out how to draw boxes properly.
Start by clarifying requirements and constraints, then design the core message lifecycle with a focus on read-once semantics and deletion. Discuss storage, delivery, and deletion mechanisms, and address trade-offs like reliability, scalability, and security.
Pro tip: Emphasize idempotency and atomicity in marking messages as read to prevent double-reads, and consider using a time-to-live (TTL) as a fallback for deletion.
Ask questions to understand scale, latency, consistency, and security needs. Determine if messages should be deleted after read or after a timeout, and if multi-device support is required.
Outline the main components: client, API gateway, message service, storage, and notification system. Sketch the flow of sending and reading a message.
Choose a database (e.g., NoSQL for scalability) and design the message schema with fields like ID, sender, recipient, content, status, and TTL. Consider encryption for security.
Design the read operation to atomically mark the message as read and delete it. Use transactions or compare-and-swap to prevent race conditions. Discuss delivery guarantees (at-most-once vs. at-least-once).
Address scaling with sharding, replication, and caching. Discuss handling failures, retries, and ensuring messages are not lost or read multiple times.
AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.