Machine Learning Engineer, Ads Optimization

About the role

Join Reddit's Ads Optimization team to build and refine the systems that power our advertising marketplace. You will focus on developing sophisticated algorithms for ad auctions, bidding, and budget management, directly impacting advertiser success and the overall health of our platform. This is a chance to work on internet-scale challenges at the core of Reddit's revenue.

Key facts

What you'll do

Develop and implement algorithms for ad auctions, bidding strategies, and budget pacing to balance advertiser performance, user experience, and marketplace efficiency.

Take ownership of systems from initial concept and algorithm design through to experimentation, production deployment, and continuous improvement.

Collaborate across the Ads Optimization domain, focusing on bid strategies, budget management, and pacing to achieve measurable improvements for advertisers and users.

Lead complex, multi-quarter initiatives, define technical direction for key components of the bidding and auction systems, and mentor other engineers while remaining hands-on.

Requirements

Possess 3-5+ years of experience in building, deploying, and operating machine learning systems in a production environment. For a senior level (IC4), expect 5+ years of experience.

Demonstrate strong programming proficiency in Python, Java, Go, or similar languages, with a solid foundation in software engineering principles.

Have experience designing and working with scalable data processing systems such as Spark, Kafka, Airflow, BigQuery, or Redis.

Show an ability to translate ambiguous product or business challenges into actionable solutions and improve key metrics.

Exhibit strong mathematical and optimization skills, evidenced by a degree in a quantitative field (e.g., math, physics, economics, operations research) or equivalent work experience in optimization-heavy domains.

Be comfortable reasoning about and implementing custom optimization logic, not just using off-the-shelf tools.

Nice to have

Experience with advertising or auction systems, online marketplaces, or large-scale search/ranking systems.

Familiarity with 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 teams (Product, Data Science, Engineering) in advertising or marketplace contexts and leading projects from inception to launch.

An advanced degree (MS or PhD) in Computer Science, Machine Learning, Operations Research, Applied Math, or a related quantitative discipline.

Skills & tools

Python, Java, Go, Spark, Kafka, Airflow, BigQuery, Redis

Practical notes

This role may be recorded, transcribed, and summarized by AI during interviews. You will have the option to opt out. Personal information collected will be used for evaluation purposes and will not be sold or shared for marketing. Recordings will be deleted after a hiring decision is made. Reddit is an equal opportunity employer and provides reasonable accommodations for individuals with disabilities.