Machine Learning Engineer, Ads Optimization & Ads Marketplace Quality

Reddit is a community of communities. It’s built on shared interests, passion, and trust, and is home to the most open and authentic conversations on the internet. Every day, Reddit users submit, vote, and comment on the topics they care most about. With 100,000+ active communities and approximately 126 million daily active unique visitors, Reddit is one of the internet’s largest sources of information. For more information, visit www.redditinc.com. Team Description This role sits in the Ads Optimization and Ads Marketplace Quality (AMQ) organizations, which are responsible for the health and performance of Reddit’s ads marketplace. We focus on: Designing the auction and bidding mechanisms that decide which ads show to which users and at what price. Building optimization systems that help advertisers achieve their goals (e.g., conversions, ROAS) under budget and delivery constraints. Ensuring marketplace quality by improving user experience with ads, fighting ad blindness, and increasing valuable ad opportunities on the platform. You’ll join a set of tight-knit engineers working on high-impact, internet-scale problems at the core of Reddit’s revenue engine, collaborating closely with Product, Data Science, and Infra partners across Reddit Ads. Role Description We are hiring Machine Learning Engineers (IC3 and IC4) to build and evolve the auction, bidding and budgeting systems that power Reddit Ads. In this role, you will: Design and implement optimization algorithms for auctions, bidding strategies, and pacing that balance advertiser performance, user experience, and marketplace efficiency. 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) to deliver measurable wins for advertisers and Redditors.