Senior
Own the auction, bidding, and pacing algorithms that power Reddit's ads marketplace
Reddit is hiring an IC3/IC4 Machine Learning Engineer to design and ship the optimization algorithms behind its ad auctions, bidding strategies, and budget pacing. Expect deep discussion of ML systems in production, optimization math, and how you'd translate business goals like ROAS into constrained optimization problems.
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What this interview tests
- Auction & bidding mechanism design
- Budget pacing and spend allocation under constraints
- Translating business objectives (ROAS, CPA, CTR/CVR) into optimization problems
- Production ML system ownership (design through deployment and iteration)
- Scalable data infrastructure (Spark, Kafka, Airflow, BigQuery, Redis)
- Marketplace quality (ad matching, ad load, relevance signals)
Common question themes
Design a bidding algorithm for a ROAS-based advertiser objective
How would you pace an advertiser's budget smoothly across a day without overspend
Formulate ad load/quality trade-offs as a constrained optimization problem
Walk through an ML system you took from problem formulation to production
How do you validate an auction change didn't hurt user experience
Gradient-based or custom optimization logic you've implemented beyond off-the-shelf tooling
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