Senior Software Engineer, Experimentation

About the Team

Our team owns the products that help teams test, ship, and observe what they build: Experiments, Feature Flags, Session Replay, and Heatmaps. Our vision is to make Mixpanel the one place where product teams roll out a change, measure its impact, see how real users experience it, and decide what to do next, all on the same event data they already trust.

These products are one of Mixpanel's most promising paths to growth. They extend Mixpanel from understanding what users do to acting on it, and they're a big part of how our customers grow with us. They also matter more in the AI era, not less. Teams are shipping faster than ever, and they need tools that tell them, just as fast, whether what they shipped is working.

What we own:

• Experiments: Controlled experiments that run on the same behavioral data customers already analyze in Mixpanel, with results teams can trust when they decide what to ship
• Feature Flags: Safe, gradual rollouts targeted by real user behavior, powered by a high-throughput evaluation service that runs in the critical path of our customers' products
• Session Replay and Heatmaps: A view of how real people experience a product across web and mobile, so teams can see the why behind the numbers

About the Role

As a Senior Software Engineer on the team, you'll own the technical design and delivery of features across Experiments, Feature Flags, Session Replay, and Heatmaps. You'll work across the full stack, from React frontend experiences to Python backend services to high-throughput systems like flag evaluation and replay ingestion. You'll partner directly with Product and Design to shape where these products go next, and collaborate with teams like AI Engine and Product Platform on shared systems and the SDKs that power our products.

This is a high-impact role on a small, senior team where you'll have significant influence over the technical direction of products that are central to Mixpanel's growth.

Responsibilities

• Own technical design for complex features end to end, from backend services and data models to frontend experiences
• Make well-reasoned technical decisions that balance speed, quality, cost, and product considerations, anticipating problems and developing contingency plans
• Drive reliability, observability, and operational excellence for services that customers depend on in production, addressing tech debt before it becomes a long-term problem
• Partner with AI Engine to bring AI into how customers design, run, and understand experiments and replays
• Collaborate with Product Platform and other teams on SDKs, shared infrastructure, and architectural decisions that affect the broader platform
• Mentor engineers on the team through code reviews, pairing, and 1:1 support, helping them grow technically
• Serve as an escalation point for complex bugs and on-call incidents in the team's domain
• Work with Support and Solutions Engineering on customer escalations and technical questions from prospects
• Partner with Product and Design to identify and lead areas of future work beyond the current roadmap

We're Looking For Someone Who Has

• Bachelor's degree in Computer Science, Mathematics, a related field, or equivalent practical experience
• 5+ years of professional software engineering experience with a proven track record of delivering quality solutions with speed
• Experience building and operating production systems end to end, with real ownership of reliability and correctness in a product customers depend on
• Expert-level depth in at least one area (systems, web, or data infrastructure) with broad understanding of full-stack architecture
• Experience owning technical design for complex projects and managing multiple concurrent workstreams
• Strong cross-functional collaboration skills: you work effectively with other teams and organizational stakeholders with little guidance
• Sound judgment in setting priorities, selecting technologies, and making tradeoffs that factor in technical, product, and business considerations
• A track record of mentoring other engineers and contributing to team growth
• Strong technical communication, ideally with experience collaborating in an asynchronous remote environment
• A desire to help teams build and decide faster in the AI era

Bonus Points For

• React / TypeScript experience
• Django / Python experience
• Experience with experimentation, feature flagging, or session replay products, as a builder or a heavy user
• Experience building high-throughput, low-latency services
• Familiarity with analytics or observability platforms
• Experience building with LLMs, AI agents, or tool-use frameworks
• Comfort using AI coding tools (Claude Code, Cursor, etc.) in your daily work

Additional Resources

• Engineering Life Page
• Engineering Blog