Machine Learning Engineer, Ads Optimization

Details

Reddit is hiring Machine Learning Engineers (IC4) to build and evolve the auction, bidding, and budgeting systems that power Reddit Ads. The role focuses on internet-scale optimization problems across Reddit's advertising marketplace and involves close collaboration with Product, Data Science, and Infrastructure teams.

Responsibilities

Auction, Bidding, And Pacing Systems

• Design and implement optimization algorithms for auctions, bidding strategies, and pacing that balance advertiser performance, user experience, and marketplace efficiency.
• Compute bids for different optimization objectives, including CPC, CPA, and ROAS-based strategies.
• Pace budgets smoothly over time across accounts, campaigns, and ad groups while preventing overspend or underspend.
• Allocate spend and auction participation across segments, surfaces, and time zones.
• Translate product and marketplace goals into concrete optimization problems and constraints, including ROI, revenue, delivery smoothness, fairness, and user experience.
• Own systems end-to-end, from problem formulation and algorithm design to experimentation, production deployment, and ongoing iteration.
• Lead complex or multi-quarter initiatives, set technical direction for key parts of the bidding, auction, and pacing stack, and mentor other engineers while remaining hands-on.

Requirements

• 3–5+ years of experience building, deploying, and operating machine learning systems in production; IC4 candidates typically have 5+ years of experience.
• Strong programming skills in Python, Java, Go, or similar languages, with solid software engineering fundamentals.
• Experience designing scalable data processing systems such as Spark, Kafka, Airflow, BigQuery, or Redis.
• Ability to translate ambiguous product or business problems into solutions and improve measurable metrics.
• Strong math and optimization skills, including a degree or equivalent background in mathematics, physics, quantitative finance, economics, operations research, or a similar quantitative field.
• Experience in optimization-heavy domains such as bidding, auctions, pacing, pricing, logistics optimization, or quantitative finance.
• Comfort reasoning about and implementing custom optimization logic, including gradient-based methods and constraint handling.

Preferred Qualifications

• Experience with advertising or auction systems, online marketplaces, or search and ranking systems at scale.
• Experience with bidding, pacing, budget optimization, auction design, mechanism design, marketplace quality, or campaign performance optimization involving CTR, CVR, CPA, or ROAS.
• Familiarity with large-scale, real-time decision systems and low-latency production environments.
• Background in feature engineering, model optimization, and production monitoring for machine learning systems.
• Experience collaborating with Product, Data Science, and Engineering partners in advertising or marketplace contexts and leading projects from design through rollout.
• Advanced degree, such as an MS or PhD, in Computer Science, Machine Learning, Operations Research, Applied Mathematics, or a related quantitative field.

Potential Teams

• Ads Optimization, including bid strategies, conversion and ROAS optimization, pacing, and budget allocation.

Benefits

• Comprehensive healthcare benefits and income replacement programs.
• 401(k) with employer match.
• Global benefit programs supporting workspace, professional development, and caregiving.
• Family planning support.
• Gender-affirming care.
• Mental health and coaching benefits.
• Flexible vacation and paid volunteer time off.
• Generous paid parental leave.

Compensation

The base salary range for this position is $216,700–$303,400 USD. The role is also eligible for equity in the form of restricted stock units and, depending on the position offered, may be eligible for a commission. Final offers depend on factors including skills, depth of experience, and relevant credentials.

Interviews for select roles and locations may be recorded, transcribed, and summarized by artificial intelligence, with an option to opt out before scheduled interviews. Reddit is an equal opportunity employer and provides reasonable accommodations for qualified individuals with disabilities and disabled veterans.