Senior Software Engineer, Site Defense

Location: Seattle, WA

Department: BE Platform

We are looking for a Senior Software Engineer to join the Site Defense team within Reddit’s Infrastructure organization. Site Defense is responsible for protecting Reddit at internet scale—serving as the first line of defense against DDoS attacks, automated abuse, large-scale scraping, and other network-level threats. This is a high impact role that sits at the intersection of distributed systems, networking, security, and applied machine learning. You will help design and operate critical infrastructure that safeguards Reddit’s availability, performance, and trust.

You will:

• Design, build, and operate high-scale, low-latency systems that protect Reddit from DDoS attacks, bots, and automated abuse.
• Analyze, develop and evolve ingress-level defenses across CDN, edge, and internal infrastructure layers.
• Build systems to detect, score, and mitigate malicious traffic in real time at per-request and per-user granularity
• Partner closely within Infrastructure and with Security, and internal Safety teams to balance security, performance, and user experience
• Mentor junior engineers in their professional growth.
• Contribute to the team’s ML-at-Ingress initiatives, including experimenting with models for traffic classification, bot detection, and anomaly detection
• Own services end-to-end, including design, implementation, on-call, and operational excellence
• Participate in incident response and post-incident analysis for large-scale network or abuse events

You have:

• 5+ years of experience building and operating high throughput and low latency production distributed systems.
• Software development experience in one or more general purpose programming languages; Python, Go, Rust, Java, C++.
• Excellent communication skills to collaborate with a service-oriented team and company.
• Experience with DDoS mitigation, WAFs, bot management, or abuse prevention systems.
• Experience with networking fundamentals (HTTP, TLS, TCP/IP, proxies, CDNs, load balancing).

Nice to have:

• Prior experience with cloud infrastructure systems (Kubernetes, AWS / GCE ecosystems).
• Familiarity with ML systems in production, especially real-time inference or feature pipelines.
• Knowledge of traffic analysis, anomaly detection, or large-scale telemetry systems.

Benefits:

• Comprehensive Healthcare Benefits and Income Replacement Programs
• 401k with Employer Match
• Global Benefit programs that fit your lifestyle, from workspace to professional development to caregiving support
• Family Planning Support
• Gender-Affirming Care
• Mental Health & Coaching Benefits
• Flexible Vacation & Paid Volunteer Time Off
• Generous Paid Parental Leave 

#LI-remote, #LI-JS5