Machine Learning Engineer, Ads Optimization & Ads Marketplace Quality

Reddit is a robust community of communities, built on shared interests, passion, and trust. It serves as a home for open and authentic conversations online, with millions of users engaging daily through submissions, votes, and comments. Reddit is a significant source of information, powered by over 100,000 active communities. For more details, visit www.redditinc.com.

Introduction

Reddit is a community built on shared interests, passion, and trust, hosting authentic conversations. With over 100,000 active communities and approximately 126 million daily active unique visitors, it's a significant source of information. This role focuses on the Ads Optimization and Ads Marketplace Quality (AMQ) organizations, essential for the health and performance of Reddit’s advertising ecosystem. This involves designing auction and bidding mechanisms, building optimization systems for advertisers, and ensuring marketplace quality by improving user ad experience.

Responsibilities

Auction, Bidding, and Pacing Systems

• Design and implement models and policies to:
  • Compute bids for various optimization objectives (e.g., CPC, CPA, ROAS-based strategies).
  • Smoothly pace budgets across accounts, campaigns, and ad groups, preventing over/underspend.
  • Intelligently allocate spend and auction participation across segments, surfaces, and time zones.
• Translate product and marketplace goals into concrete optimization problems and constraints (e.g., ROI, revenue, delivery smoothness, fairness, user experience).

Marketplace Quality and Optimization

• Partner with Ads Marketplace Quality to:
  • Enhance ad matching and ranking by integrating new quality and relevance signals into bidding and auction decisions.
  • Develop policies for ad load and eligibility to protect user experience while creating high-quality ad opportunities.
• Collaborate with Ads Optimization to integrate new bid strategies and pacing mechanisms into the broader ads ecosystem and measurement stack.

Requirements

• Experience: 3–5+ years (IC3) or 5+ years (IC4) building, deploying, and operating machine learning systems in production.
• Programming Skills: Strong proficiency in Python, Java, Go, or similar languages, with solid software engineering fundamentals.
• Data Processing: Experience designing scalable data processing systems (e.g., Spark, Kafka, Airflow, BigQuery, Redis).
• Problem Solving: Demonstrated ability to translate ambiguous product or business problems into solutions and improve measurable metrics.

Additional expectations for strong bidding/auction candidates (especially IC4):

• Math & Optimization: Strong mathematical and optimization skills, evidenced by:
  • Degree or background in a quantitative field (math, physics, quantitative finance, economics, operations research).
  • Work experience in optimization-heavy domains (e.g., bidding/auctions, pacing, pricing, logistics optimization, quantitative finance).
• Custom Optimization Logic: Comfort with reasoning about and implementing custom optimization logic (e.g., gradient-based methods, constraint handling), not just black-box tooling.

Nice to Have

• Experience with advertising/auction systems, online marketplaces, or search/ranking systems at scale, particularly in:
  • Bidding, pacing, or budget optimization.
  • Auction design, mechanism design, or marketplace quality.
  • Campaign performance optimization (e.g., CTR/CVR, CPA, ROAS).
• Familiarity with large-scale, real-time decision systems and low-latency production environments.
• Background in feature engineering, model optimization, and production monitoring for ML systems.
• Experience collaborating with cross-functional partners (Product, DS, Eng) in Ads or marketplace contexts and leading projects from design through rollout.
• Advanced degree (MS or PhD) in Computer Science, Machine Learning, Operations Research, Applied Math, or a related quantitative field.

Benefits

• Comprehensive Healthcare Benefits and Income Replacement Programs
• 401k with Employer Match
• Global Benefit programs for workspace, professional development, and caregiving support
• Family Planning Support
• Gender-Affirming Care
• Mental Health & Coaching Benefits
• Flexible Vacation & Paid Volunteer Time Off
• Generous Paid Parental Leave

About Company

Reddit is a robust community of communities, built on shared interests, passion, and trust. It serves as a home for open and authentic conversations online, with millions of users engaging daily through submissions, votes, and comments. Reddit is a significant source of information, powered by over 100,000 active communities. For more details, visit www.redditinc.com.

How to Apply

To apply for this position, please use the provided application link. The interview process may involve recording, transcription, and summarization by AI, with an opt-out option available. Reddit is an equal opportunity employer committed to a diverse workforce and provides reasonable accommodations for qualified individuals with disabilities.