System Design Interview Mock

Free system design interview practice. Work through a 50-minute mock interview in six timed phases, from requirements and estimation to deep dives and failure modes, then export your answer as Markdown for AI feedback.

System design interview questions

• TinyURL shortener service (easy)
• Conversation history for a chat assistant (medium)
• LLM inference gateway (hard)
• Token-based rate limits (medium)
• Usage metering and billing (hard)
• Webhook delivery (medium)
• Batch inference API (hard)
• File search for assistants (hard)
• Model evaluation runner (medium)
• Code execution sandbox (hard)
• Notification service (medium)