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Machine Learning Engineer, Ads Optimization & Ads Marketplace Quality

Build and evolve auction, bidding, and budgeting ML systems that power Reddit Ads. Design optimization algorithms balancing advertiser performance, user experience, and marketplace efficiency.

186k – 303kUnited StatesML EngineeringRemote3+ YOE

About the role

Responsibilities

Auction, Bidding, and Pacing Systems

  • Design and implement models and policies that compute bids for different optimization objectives (CPC, CPA, ROAS-based strategies).
  • Pace budgets smoothly over time across accounts, campaigns, and ad groups while preventing overspend or underspend.
  • Allocate spend and auction participation intelligently across segments, surfaces, and time zones.
  • Translate product and marketplace goals into concrete optimization problems and constraints (ROI, revenue, delivery smoothness, fairness, user experience).

Marketplace Quality and Optimization

  • Improve ad matching and ranking by incorporating new quality and relevance signals into bidding and auction decisions.
  • Inform policies around ad load and eligibility that protect user experience while increasing high-quality ad opportunities.
  • Integrate new bid strategies and pacing mechanisms into the broader ads ecosystem and measurement stack.

General

  • Own systems end-to-end: from problem formulation and algorithm design to experimentation, production deployment, and ongoing iteration.
  • Work across Ads Optimization (bid strategies, budget optimization, pacing) or Ads Marketplace Quality (ad matching, ad load, quality controls).

Requirements

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

Preferred Qualifications

  • Experience with advertising/auction systems, online marketplaces, or search/ranking systems at scale.
  • Experience in bidding, pacing, budget optimization, auction design, mechanism design, marketplace quality, or campaign performance optimization (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.
  • 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 (workspace, professional development, caregiving support)
  • Family Planning Support
  • Gender-Affirming Care
  • Mental Health & Coaching Benefits
  • Flexible Vacation & Paid Volunteer Time Off
  • Generous Paid Parental Leave

Skills

PythonJavaGoSparkKafkaAirflowBigQueryRedisMachine LearningOptimization AlgorithmsBidding SystemsAuction DesignPacingBudget Optimization

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