
Senior Research Engineer – Post-training, Evaluation
Reddit, Inc.
full-time
Posted on:
Location Type: Remote
Location: United States
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Salary
💰 $216,700 - $303,400 per year
Job Level
About the role
- Architect and maintain the "Reddit Benchmark" evaluation suite: A comprehensive harness that rigorously tests model capabilities across Safety, Reasoning, and Reddit-specific knowledge (slang, norms).
- Build scalable SFT (Supervised Fine-Tuning) pipelines: Implement efficient, distributed training loops for instruction tuning, converting raw base models into helpful assistants.
- Develop Model-as-a-Judge systems: Engineer automated evaluation pipelines using strong models (e.g., GPT-5, Nova, Claude) to grade the outputs of our internal models, enabling rapid iteration cycles.
- Execute Synthetic Data generation strategies: Create and curate high-quality instruction sets to improve model generalization where human data is scarce.
- Collaborate with Safety Engineering: Translate high-level safety policies into concrete evaluation metrics and unit tests that run in our CI/CD pipelines.
- Debug post-training instability: Dive deep into loss curves and evaluation logs to identify when fine-tuning is causing alignment tax or capability degradation.
Requirements
- 4+ years of professional experience in machine learning engineering, with a focus on LLM fine-tuning or evaluation.
- Fluency in Python and PyTorch, with experience using libraries like Hugging Face Transformers, vLLM, or lm-eval-harness.
- Deep understanding of Instruction Tuning (SFT) and how data quality impacts model behavior.
- Experience building Evaluation Pipelines: You know the difference between MMLU, GSM8K, and how to build a custom domain-specific benchmark.
- Familiarity with distributed training (FSDP/DeepSpeed) for fine-tuning jobs.
- Strong data engineering skills for curating and cleaning instruction datasets.
Benefits
- Comprehensive Healthcare Benefits and Income Replacement Programs
- 401k with Employer Match
- Global Benefit programs that fit your lifestyle, from workspace to professional development to caregiving support
- Family Planning Support
- Gender-Affirming Care
- Mental Health & Coaching Benefits
- Flexible Vacation & Paid Volunteer Time Off
- Generous Paid Parental Leave
Applicant Tracking System Keywords
Tip: use these terms in your resume and cover letter to boost ATS matches.
Hard Skills & Tools
machine learning engineeringLLM fine-tuningPythonPyTorchHugging Face TransformersvLLMlm-eval-harnessInstruction TuningEvaluation Pipelinesdata engineering