Senior Software Engineer, Experimentation

Mixpanel•San Francisco, CA

About The Position

As a Senior Software Engineer on Mixpanel’s 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 and high-throughput systems such as flag evaluation and replay ingestion. You’ll partner with Product and Design to shape these products and collaborate with teams such as AI Engine and Product Platform on shared systems and SDKs. This is a high-impact role on a small, senior team, with significant influence over the technical direction of products central to Mixpanel’s growth. Mixpanel’s team builds products that help teams test, ship, and observe what they build. Its goal is to let product teams roll out a change, measure its impact, understand real user experiences, and decide what to do next using the event data they already trust. The products include controlled experiments, behavior-targeted feature flag rollouts, and Session Replay and Heatmaps for understanding user experiences across web and mobile.

Requirements

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

Nice To Haves

React / TypeScript experience.
Django / Python experience.
Experience with experimentation, feature flagging, or session replay products, as a builder or 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 such as Claude Code or Cursor in daily work.

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; anticipate problems and develop contingency plans.
Drive reliability, observability, and operational excellence for production services, and address technical 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 through code reviews, pairing, and one-on-one support to help 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.

Benefits

Comprehensive medical, vision, and dental care.
Mental wellness benefit.
Generous vacation policy and additional company holidays.
Enhanced parental leave.
Volunteer time off.
For US employees: pre-tax benefits including 401(k), wellness benefit, and holiday break. Benefits and perks for contract positions vary.

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