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Reddit

Senior

Build Reddit's LLM Gateway and GenAI platform infrastructure at scale

Interview for a Senior Software Engineer role on Reddit's Machine Learning Platform team, leading development of a large-scale GenAI Platform including an LLM Gateway with unified API endpoints, rate/token limiting, and failover. Expect deep questions on RAG systems, agentic workflows with LangChain/LangGraph, and LLMOps practices at Kubernetes scale.

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What this interview tests

  • LLM Gateway design (unified endpoints, rate limiting, failover)
  • RAG systems (embeddings, vector search, retrieval pipelines)
  • Agentic workflows with LangChain/LangGraph
  • LLMOps/MLOps practices (CI/CD, versioning, evaluation, observability)
  • Kubernetes and infrastructure-as-code at scale (Terraform)
  • Platform thinking and cross-team enablement

Common question themes

Design an LLM Gateway with failover across multiple providers

Walk through a RAG pipeline you built and how you evaluated retrieval quality

Describe an agentic workflow you implemented with LangChain or LangGraph and a failure mode you hit

How do you operationalize LLMOps practices for a GenAI pipeline in production

How have you scaled ML infrastructure on Kubernetes with Terraform

How do you design a platform that other engineering teams can self-serve on

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