Machine Learning Engineer, Ranking and Personalization

Staff Machine Learning Engineer, Developer Platform

Remote - United States

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 121 million daily active unique visitors, Reddit is one of the internet’s largest sources of information.

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The Developer Platform team is building the future of Reddit: a future where third‑party developers, moderators and everyday redditors can invent and ship brand‑new apps, games and tools that create entirely new ways for communities to play, connect and get things done  power everything from interactive custom posts and daily games to mod tooling and data products, giving builds the primitives they need to create entirely new kinds of experiences on Reddit.

Within Developer Platform, our Growth team focuses on helping redditors discover the right apps and games at the right time through ranking, notifications, and cross‑surface entry points, directly moving the needle on engagement and DAU for Dev Platform experiences. You’ll work end‑to‑end with a highly collaborative, cross‑functional group of engineers, PMs, designers, and data scientists who value impact, personal growth, openness, and kindness, and who ship quickly while holding a high bar for reliability and performance across Reddit’s web, mobile, and backend stack.

We are looking for a Staff Machine Learning Engineer, Developer Platform to build the ranking and personalization systems that connect redditors with their next favorite game or app on Reddit. You will work closely with Product, Backend, Data Science, and Core Ranking/ML Platform teams to design and ship best-in-class ranking, retrieval, and experimentation systems that power discovery and re‑engagement for Dev Platform experiences across feeds, surfaces, and notifications.

You will own problems end‑to‑end from framing objectives and defining signals, to training and deploying models, to designing experiments and reading results—not just tuning existing knobs on mature systems. You’ll help define the ranking strategy for Developer Platform, stand up new ML models and feedback loops where none exist today, and turn noisy behavioral data into clear wins for users, creators, and developers.

This is a high‑impact, 0-1 role where your work will directly shape how interactive apps and games show up on one of the largest sites in the world. You’ll set technical direction for Dev Platform ranking, raise the bar on relevance and system reliability, and mentor other engineers as we scale a team of builders who value impact, personal growth, openness, and kindness.

Languages: Go, Python, C++ or any object oriented programming language

Libraries: Baseplate, GraphQL

• Design and ship the next generation ranking and ML backend systems that power discovery of Dev Platform apps and games across Reddit surfaces.
• Partner with ML, DS, and product to define signals, APIs, and feedback loops for training, deploying, and iterating on ranking models.
• Explore and product ionize new retrieval, ranking, and experimentation approaches that unlock new Dev Platform experiences.
• Champion reliability, observability, and experimentation best practices for ranking systems.
• Mentor engineers and lead technical discussions, shaping the long‑term ranking and personalization strategy for Dev Platform.

• 8+ years of experience as a software engineer building large‑scale distributed systems and/or data‑intensive, ML‑driven systems, using Go, Python, C++, or another object‑oriented language.
• Proven track record working on cross‑functional product teams (PM, Design, DS, Eng) where you owned end‑user outcomes, not just models or infra, and shipped features that moved core product metrics.
• Experience designing and improving ML tooling and platforms: deployment and rollout, automation, experiment frameworks, system diagnosis, reproducibility, and ML monitoring/alerting.
• Experience…