Principal Software Engineer, Ads Backend Engineering

Job Description

Reddit is seeking a Principal Software Engineer to lead the technical strategy and vision for Ads Foundations, the technical backbone powering Ads Monetization at scale. This is the most senior individual contributor role in the engineering organization, designed for those who drive not only complex systems but also organizational and industry-wide influence. As Principal Engineer, the candidate will set the technical direction for how Reddit’s Ads backend evolves to meet the next generation of advertiser and user needs, with a particular focus on platform architecture, scalability, reliability, and operational excellence. The candidate will operate as a force multiplier, elevating not only systems but also engineers, the org, and the industry at large.Reddit's Ads Foundations org combines Ads Engineering, Product, ML Systems, and Experimentation efforts to show the best ad to Reddit users. Their responsibilities include tech evolution of the Reddit & Ads stack, balancing the needs of advertisers and Reddit users, engineering velocity & happiness, cloud resources & data observability, and cost of revenue tracking and optimizations.What this role involves:

• Defining and driving the long-term technical architecture and platform strategy for Reddit Ads backend systems.
• Architecting systems that power billions of ad impressions with high reliability, low latency, and cost efficiency.
• Leading cross-org and cross-functional technical initiatives that span beyond Ads.
• Championing rigorous observability, reliability engineering, and cost-aware architecture practices.
• Coaching, sponsoring, and elevating Staff and Senior Engineers across the org.
• Representing Reddit’s technical brand externally through talks, blog posts, patents, or contributions to open source.

Requirements:

• 10+ years of experience designing and operating highly scalable backend infrastructure.
• Recognized technical leader with a proven track record of driving large-scale platform transformations.
• Deep expertise in distributed systems, backend architecture, infrastructure, and performance engineering.
• Skilled at driving clarity in ambiguous spaces, influencing technical strategy across organizations.
• Exceptional collaborator and communicator — adept at aligning technical vision with business outcomes.
• Expertise in one or more general-purpose programming languages (Python, Go, Java, Rust, C++).
• Strong experience with systems observability, reliability, and operational best practices.

What Reddit offers:

• Comprehensive Healthcare Benefits and Income Replacement Programs
• 401k Match
• Family Planning Support
• Gender-Affirming Care
• Mental Health & Coaching Benefits
• Flexible Vacation & Reddit Global Days Off
• Generous paid Parental Leave
• Paid Volunteer time off