Reddit Senior Software Engineer Interview
Focus areas and question themes aggregated from 3 current openings — pick any opening below and practice a voice mock calibrated to it.
Reddit Senior Software Engineer mock interview
A live voice mock calibrated to this role — real questions, the real follow-up rhythm, and a score at the end. Free to start.
Reddit's Senior Software Engineer family spans three infrastructure-heavy specialties: the Core API Platform serving listings and comments at massive scale, the Compute Platform team building Kubernetes and multi-cloud orchestration, and the GenAI Platform team building an internal LLM Gateway. All three are senior IC roles that expect independent ownership of complex systems.
What this interview tests
- Distributed systems design at scale — Core Platform tests designing a system that serves hundreds of thousands of TPS reliably; GenAI Platform tests designing an LLM Gateway with failover across multiple providers — both push candidates to reason about scale and reliability, not just correctness.
- Infrastructure and Kubernetes depth — The Compute Platform posting goes deep on Kubernetes controllers, cluster reconciliation, and Linux internals like cgroups and namespaces for multi-tenant isolation.
- LLM/GenAI platform engineering — The GenAI Platform posting specifically tests RAG pipeline design, agentic workflows built with LangChain or LangGraph, and LLMOps practices like CI/CD and evaluation for production LLM systems.
- Incident response and independent debugging — Core Platform asks about debugging a production incident in a distributed API platform, while Compute Platform asks about a complex cross-system issue debugged independently end to end.
- Mentoring and platform ownership — Core Platform tests mentoring junior engineers through disagreement, Compute Platform tests independent ownership of large ambiguous infra projects, and GenAI Platform tests platform thinking for other teams to self-serve on.
Common question themes
Design a system that serves hundreds of thousands of TPS reliably.
Core Platform's central system-design prompt, tied to keeping a mission-critical API at high availability.
Design a Kubernetes controller to manage a specific workload's lifecycle.
Tests the cluster-orchestration depth central to the Compute Platform posting.
Explain how cgroups and namespaces isolate workloads on a shared node.
Direct Linux internals check for the infrastructure-focused Compute Platform role.
Design an LLM Gateway with failover across multiple providers.
Core system-design prompt for the GenAI Platform posting.
Walk through a RAG pipeline you built and how you evaluated retrieval quality.
Tests hands-on GenAI platform experience beyond theory.
Tell me about debugging a production incident in a distributed API platform.
Core Platform's operational-reliability check.
Describe a complex cross-system issue you debugged independently, end to end.
Compute Platform's test of ownership without hand-holding.
Likely format
None of the three postings specify interview format directly. Every question in this family leans on 'design' or 'walk through/describe a time' phrasing tied to real production systems, which suggests a technical system-design round paired with a debugging or past-incident discussion rather than a pure whiteboard-algorithms screen. Expect the specific technical focus — API platform, Kubernetes/infra, or GenAI — to depend heavily on which posting you're interviewing for.
All 3 Reddit openings in this role
Senior
Senior Software Engineer, Core Platform
Senior
Senior Software Engineer, Compute Platform
Senior
Senior Software Engineer, GenAI Platform
Frequently asked questions
Do all Reddit Senior Software Engineer roles focus on Kubernetes?
No, only the Compute Platform posting goes deep on Kubernetes and Linux internals. Core Platform is about API and distributed systems at high QPS, and GenAI Platform is about LLM infrastructure — check which specific posting you're interviewing for.
Is Go required for these roles?
Go shows up across the family — both Core Platform and Compute Platform list it explicitly as a core language for backend and infrastructure work. Python also appears on the Core Platform posting, so exact language depth expectations vary by team.
Will I need LLM or GenAI experience?
Only for the GenAI Platform posting, which explicitly tests RAG systems, LangChain/LangGraph agentic workflows, and LLMOps practices. The other two postings in this family don't mention generative AI infrastructure at all.