Senior Software Engineer Site Defense

About Reddit, Inc.

Reddit is a community of communities built on shared interests, passion, and trust, hosting open and authentic conversations on the internet. With over 100,000 active communities and approximately 121 million daily active unique visitors, Reddit stands as one of the internet's largest sources of information.

We are seeking a Senior Software Engineer Site Defense to join our Infrastructure organization's Site Defense team. This team is critical for protecting Reddit at internet scale, acting as the primary defense against DDoS attacks, automated abuse, large-scale scraping, and other network-level threats. This high-impact role blends distributed systems, networking, security, and applied machine learning to safeguard Reddit’s availability, performance, and user trust.

What You Will Do

• Design, build, and operate high-scale, low-latency systems to 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 for real-time detection, scoring, and mitigation of malicious traffic at per-request and per-user granularity.
• Collaborate closely within Infrastructure and with Security and internal Safety teams to balance security, performance, and user experience.
• Mentor junior engineers, fostering 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, encompassing design, implementation, on-call support, and operational excellence.
• Participate in incident response and post-incident analysis for large-scale network or abuse events.

What 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 such as Python, Go, Rust, Java, or C++.
• Excellent communication skills crucial for collaborating effectively within a service-oriented team and company.
• Experience with DDoS mitigation, WAFs, bot management, or abuse prevention systems.
• Experience with networking fundamentals, including HTTP, TLS, TCP/IP, proxies, CDNs, and load balancing.

Nice To Have

• Prior experience with cloud infrastructure systems (e.g., 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 tailored to 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

Key skills/competency

• Distributed Systems
• DDoS Mitigation
• Bot Management
• Network Security
• Applied Machine Learning
• Real-time Systems
• Cloud Infrastructure
• Traffic Analysis
• Incident Response
• Operational Excellence