Roblox Software Engineer Interview Questions

Behavioral Questions (15)

1. 1.Tell me about a time you had to optimize performance in a real-time system where latency directly impacted user experience. What was causing the bottleneck and how did you solve it?

   easy~3 min

   What interviewers look for

   • Demonstrates understanding of real-time performance constraints and user impact
   • Shows systematic approach to identifying bottlenecks through profiling or monitoring
   • Explains trade-offs between different optimization approaches and their long-term implications

   Likely follow-ups

   • How did you measure the impact of your optimization on actual users?
   • What monitoring did you put in place to catch similar issues in the future?

   Company context

   Roblox runs one of the largest real-time 3D multiplayer platforms, where frame drops or network latency directly impact millions of users' experiences. The Real-Time 3D Engineering principle requires engineers to think about graphics, physics, and networking performance holistically, especially given Roblox's cross-platform constraints from mobile to console.

2. 2.You're working on Roblox Studio's Lua debugger and notice that stepping through code becomes unusably slow when there are more than 10,000 objects in the workspace. How would you approach diagnosing and fixing this performance issue?

   easy~3 min

   What interviewers look for

   • Identifies that the debugger likely iterates over all workspace objects on each step, causing O(n) overhead per debugging operation
   • Proposes profiling the debugger itself to identify bottlenecks, potentially using sampling or instrumentation to measure where time is spent
   • Suggests optimizations like caching object metadata, lazy evaluation of object properties, or implementing incremental updates instead of full traversals

   Likely follow-ups

   • What if the performance issue only happens with specific types of objects, like MeshParts or unions?
   • How would you ensure your fix doesn't break existing Studio workflows that developers rely on?

   Company context

   Roblox Studio is the primary tool creators use to build experiences on the platform. Performance issues in Studio directly impact developer productivity and the quality of content created. This question tests understanding of debugging tools, performance optimization, and the Creator Economy ecosystem that Roblox depends on. It also relates to Roblox's 'Get Stuff Done' value by focusing on removing blockers for developers.

3. 3.Design a system for Roblox developers to upload and distribute assets like meshes, textures, and audio through the marketplace. The system needs to handle 100,000 uploads daily while ensuring content safety for younger users.

   easy~3 min

   What interviewers look for

   • Separate content storage from moderation pipeline with async processing to handle upload volume
   • Multi-stage moderation including automated scanning, human review queues, and post-publish community reporting
   • Asset versioning and rollback capabilities for when moderation flags previously approved content
   • CDN distribution strategy considering global developer and player base

   Likely follow-ups

   • How would you handle a scenario where a popular asset gets flagged after 10,000 experiences are already using it?
   • What specific safety checks would you implement for audio uploads given Roblox's younger audience?

   Company context

   Roblox's Developer Economy paid out over $1B to creators, but the platform's commitment to 'Respect the Community' means every user-generated asset must be safe for younger users. This tests understanding of content moderation at scale while maintaining developer velocity.

4. 4.Tell me about a time you took initiative on a project without being explicitly asked to lead it. What made you step up, and how did you get buy-in from others?

   easy~3 min

5. 5.A Roblox developer reports that their experience loads fine on PC but takes 45 seconds to load on mobile, causing most players to quit before it starts. Estimate how much potential revenue this developer is losing per month and walk me through your assumptions.

   easy~3 min

6. 6.Describe a feature you built where you had to consider the safety implications for younger users. What specific safety concerns did you identify and how did you address them?

   medium~4 min

7. 7.We need to implement a feature where players can report inappropriate behavior in voice chat, but the report needs to include the last 30 seconds of audio for moderation review. How would you architect this system considering our real-time voice infrastructure?

   medium~4 min

8. 8.Roblox Studio needs to sync project files between team members working on the same experience. Design a collaborative editing system that handles merge conflicts when multiple developers edit the same Lua script or 3D scene simultaneously.

   medium~4 min

9. 9.Describe a situation where you had to convince a team to make a technical decision that would be better for the platform long-term but slower to ship in the short-term. How did you approach that conversation?

   medium~4 min

10. 10.We're seeing a 15% drop in new developer signups for Roblox Studio week-over-week, but our marketing spend and feature releases haven't changed. How would you investigate what's causing this decline?

    medium~4 min

11. 11.Walk me through a time you had to design an API or system that external developers would use to monetize their content. How did you balance developer needs with platform sustainability?

    hard~5 min

12. 12.Roblox experiences can have thousands of concurrent players, but our current server architecture assigns each experience to a single game server. A popular experience is hitting CPU limits and we need to support horizontal scaling across multiple servers. Design a system that allows a single experience to run across multiple game servers while maintaining the real-time multiplayer feel.

    hard~5 min

13. 13.Design a cross-platform input system for Roblox that translates player actions between PC keyboard, mobile touch, Xbox controller, and VR controllers while maintaining identical gameplay across all platforms.

    hard~5 min

14. 14.Tell me about a time you identified a significant risk to user safety or developer trust in a system you were working on. How did you escalate it and what was the outcome?

    hard~5 min

15. 15.Estimate how many additional trust and safety moderators Roblox would need to hire if we enabled real-time voice chat in all experiences instead of just age-verified users in select experiences. Walk through your reasoning.

    hard~5 min