← Openai Interview Insights

Openai·Software Engineer·Onsite - System Design / Architecture·Senior

SeniorPrefer not to say
Jun 2026

Summary

System design round at OpenAI for a software engineer role. The prompt was to design a cloud-based IDE sandbox, and the conversation went pretty deep into execution internals inside the VM. Felt okay on the high-level design but got a bit shaky when pressed on the lower-level stuff.

Questions Asked (1)

Q1

Design a cloud-based IDE sandbox that can execute user-submitted code.

System DesignTechnical Trade-offs
Author's notes

Spent most of the time on the workflow: how a user submits code, how it gets routed to a VM, results coming back.

Create a free account to read the full note

AI HintsAI Generated

Suggested Approach

Start by clarifying requirements: supported languages, execution time limits, security, and scale. Then propose a high-level architecture with isolated sandboxes (e.g., containers or microVMs), a job queue, and resource limits, and discuss trade-offs between isolation, performance, and cost.

Pro tip: Emphasize security and isolation as the top priority, and mention that you'd use defense-in-depth with multiple layers (e.g., seccomp, AppArmor, network isolation) to prevent sandbox escapes.

1. Clarify Requirements

Ask about supported languages, expected load, execution time limits, and security requirements to scope the design.

2. High-Level Architecture

Outline components: API gateway, job queue, sandbox orchestrator, execution workers, and result storage. Describe the flow from code submission to result retrieval.

3. Sandbox Isolation

Choose an isolation technology (containers, microVMs, gVisor) and explain how to enforce resource limits (CPU, memory, disk, network) and prevent escapes.

4. Scalability and Reliability

Discuss horizontal scaling of workers, queue management, handling failures, and monitoring. Mention autoscaling and load balancing.

5. Trade-offs and Alternatives

Compare options (e.g., containers vs. microVMs) in terms of security, performance, and cost. Explain your choices based on requirements.

Key Points to Mention

  • Use of lightweight virtualization (e.g., Firecracker microVMs) for strong isolation with low overhead.
  • Resource limiting via cgroups, namespaces, and seccomp to prevent resource exhaustion and syscall abuse.
  • Network isolation: disable outbound network or restrict to allowlist to prevent data exfiltration.
  • Job queue and asynchronous processing to handle bursts and ensure fairness.
  • Security best practices: run as non-root, read-only filesystem, regular patching, and monitoring for anomalies.
  • Caching and warm pools to reduce cold-start latency for frequently used runtimes.

AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.