Reddit, Inc. · 5 hours ago
Senior Research Engineer, Post-training & Evaluation
United States
Full-time
Remote
Mid, Senior Level
$217K/yr - $303K/yr
4+ years expReddit is a community of communities, and they are seeking a Senior Research Engineer for Post-training & Evaluation to join their AI Engineering team. This role involves architecting evaluation suites and fine-tuning pipelines for large language models to ensure they are safe and effective for Reddit's unique environment.
PublishingSocial MediaDigital MediaContentNewsSocial Network
Responsibilities
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
Qualification
Required
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
Preferred
Experience with MLFlow, Weights & Biases, or other experiment tracking tools
Experience with Synthetic Data generation (e.g., Self-Instruct papers)
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
Company
Reddit, Inc.
Reddit is the heart of the internet, where millions of people get together to talk about any topic imaginable.
1001-5000 employees
H1B Sponsorship
Reddit, Inc. has a track record of offering H1B sponsorships. Please note that this does not
guarantee sponsorship for this specific role. Below presents additional info for your
reference. (Data Powered by US Department of Labor)
Distribution of Different Job Fields Receiving Sponsorship
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Trends of Total Sponsorships
2025 (99)
2024 (63)
2023 (76)
2022 (70)
2021 (68)
2020 (39)
Funding
Current Stage
Public CompanyTotal Funding
$1.33BKey Investors
FidelityVy CapitalTencent
2024-03-21IPO
2021-08-12Series F· $410M
2021-02-08Series E· $367.95M
Leadership Team
Steve Huffman
CEO
Chris Slowe
CTO
Recent News
2026-02-09
Company data provided by crunchbase