Build the real-time messaging infrastructure that connects tens of millions of Roblox users

Roblox is hiring a Senior Software Engineer (5+ years) for its Communications Platform team in San Mateo, CA, owning the systems behind chat, direct messaging, forums, comments, real-time socket messaging, streaming, and search at global scale. The role is end-to-end ownership: design docs through production operation, API/client library design for internal and creator-facing use, and safety as a first-class design constraint.

Practice this interview

Free · a live voice mock calibrated to this exact role

Start the mock interview

What this interview tests

Real-time messaging/socket infrastructure at scale
API and client library design for internal + external (creator) consumers
End-to-end project ownership from design doc to production
Safety-by-design in communication systems
Production reliability, on-call, performance improvement
Server-side language depth (C#, Java, Go, or C++)

Common question themes

Design a real-time chat/messaging system for tens of millions of concurrent users

Walk through an API or client library you designed for other teams to consume

Tell me about leading a technical initiative end-to-end, including a design doc you authored

How would you build safety constraints into a communications feature from the start

Describe a production reliability issue you owned and the fix that stuck

How do you make architectural decisions that hold up under scale growth

How candidates describe it

Real Senior Software Engineer (Backend / Full Stack) interview stories — retold from candidates' public write-ups, with sources.

Google · Backend Software EngineerNo offer

Google Backend Engineer Interview Experience: Bangalore Onsite (Rejected)

A rejected Google Backend Engineer candidate in Bangalore recounts a recruiter screen, a gating elimination round, and a three-round onsite loop covering trees, tries, scheduling, and graph problems.

Interviewed April 2021 · Bangalore, India

Google · L3 Software EngineerOffer

Google L3 software engineer interview: phone screen, four coding rounds, and the Googleyness round

A candidate with two years of experience went from recruiter outreach to offer over about four months. The onsite was four 45-minute coding rounds — three of them featuring binary trees — and one round turned into a 25-minute chain of follow-ups about approximating an optimal solution at scale.

Interviewed June 2020 · Bangalore, IN

Google · L4 Software EngineerNo offer

Google L4 Software Engineer Interview: Eight Rounds, No Offer

An L4 Software Engineer candidate went through two phone screens, three onsite rounds, a culture conversation, and a team-matching call with a Google hiring manager, then watched the process stall for about a month and a half over a tightened experience requirement before an added extended round ended without an offer.

Interviewed February 2024 · Not specified

View the original posting

All Roblox interviews