Reddit - Staff Research Engineer, Pre-training Data
Requirements
• 8+ years of software engineering experience with a focus on machine learning infrastructure, data science at scale, or LLM pre-training. • Expert proficiency in Python and distributed data processing frameworks (e.g., Ray Data, Spark, or custom high-performance dataloaders). • Experience handling Unstructured and Semi-Structured data at scale (not just tabular data)—specifically text, code, images, and audio/video. • Strong mathematical foundation in probability, statistics, and importance sampling theory. • Deep understanding of pre-training dynamics and the impact of data quality/ordering on model performance. • Experience working with Graph data structures or serializing conversation trees is highly valued. • Experience with JAX or PyTorch internals related to distributed data loading • Experience with Multimodal datasets (image/video + text) and vision-language preprocessing. • Proficiency in Rust or C++ for performance-critical data path optimization. • Published research or significant practical experience in active learning or automated data selection.
Responsibilities
• Architect and implement high-throughput, deterministic data sampling systems capable of feeding distributed training clusters at frontier-model scale. • Design and execute dynamic curriculum learning strategies, creating systems that automatically adjust data distributions (text vs. multimodal) during training to improve model stability and reasoning capabilities. • Engineer the logic for serializing Reddit’s complex conversational trees (threads, subreddits, cross-posts) into optimal training contexts, developing topological data processing strategies that preserve semantic relationships for model understanding. • Formulate and validate statistical hypotheses regarding data mixtures, leveraging advanced sampling theory to minimize bias and maximize token quality. • Design the "Safety-First" ingestion layer: Build automated pipelines for PII redaction, toxicity signals, and quality deduplication upstream of training, working closely with our Safety and Moderation Engineering counterparts. • Bridge the gap between research and engineering by translating theoretical sampling insights into robust, low-latency production infrastructure. • Mentor senior engineers and researchers on system design, numerical correctness, and performance optimization within distributed Python/Rust environments.
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 • Pay Transparency: • Pay Transparency: • This job posting may span more than one career level. • In addition to base salary, this job is eligible to receive equity in the form of restricted stock units, and depending on the position offered, it may also be eligible to receive a commission. Additionally, Reddit offers a wide range of benefits to U.S.-based employees, including medical, dental, and vision insurance, 401(k) program with employer match, generous time off for vacation, and parental leave. To learn more, please visit https://www.redditinc.com/careers/. • To provide greater transparency to candidates, we share base salary ranges for all US-based job postings regardless of state. We set standard base pay ranges for all roles based on function, level, and country location, benchmarked against similar stage growth companies. Final offer amounts are determined by multiple factors including, skills, depth of work experience and relevant licenses/credentials, and may vary from the amounts listed below. • The base salary range for this position is: • $230,000 - $322,000 USD • In select roles and locations, the interviews will be recorded, transcribed and summarized by artificial intelligence (AI). You will have the opportunity to opt out of recording, transcription and summarization prior to any scheduled interviews. • During the interview, we will collect the following categories of personal information: Identifiers, Professional and Employment-Related Information, Sensory Information (audio/video recording), and any other categories of personal information you choose to share with us. We will use this information to evaluate your application for employment or an independent contractor role, as applicable. We will not sell your personal information or disclose it to any third party for their marketing purposes. We will delete any recording of your interview promptly after making a hiring decision. For more information about how we will handle your personal information, including our retention of it, please refer to our Candidate Privacy Policy for Potential Employees and Contractors.
Apply in one click
Upload My Resume
Drop here or click to browse · Tap to choose · PDF, DOCX, DOC, RTF, TXT