Senior Software Engineer, MediaWiki

Summary

The Wikimedia Foundation is looking for a Senior Software Engineer to join the MediaWiki Platform team. MediaWiki is the open-source platform that powers Wikipedia and its sister projects - impacting hundreds of millions of Wikipedia users across the globe.

The MediaWiki Platform team builds and maintains the core of MediaWiki as well as the components responsible for authentication, notifications, and media management. The team’s mission is to provide a solid foundation for feature teams to build on. It focuses on performance, reliability and scalability, helping to ensure broad and equitable access to free knowledge.

This role offers a unique opportunity to combine technical depth with mission-driven impact. As a Senior Engineer, you will not only write robust code but also lead by example, prioritize high-impact work, support better decision-making through metrics and observability and foster a culture of accountability, transparency, and continuous improvement.

You will be responsible for:

• Designing, improving, and maintaining key parts of the MediaWiki stack;
• Driving technical quality and operational excellence by defining and reinforcing standards in testing, observability, and system reliability;
• Comfortably and autonomously creating proofs of concept, writing design documents, and breaking down complex projects into actionable tasks to support less experienced team members;
• Developing and improving shared capabilities (e.g., authentication, caching, rate limiting) that enable other teams to build efficiently and consistently;
• Championing key product metrics by focusing on measurable outcomes that guide our decisions and help us to evaluate success;
• Leading by example in code review, decision-making, and team culture - fostering transparency, empathy, and collaboration;
• Improving and automating processes for identifying, tracking, and resolving production issues;
• Collaborating with the Product team and the community to ensure technical solutions align with WMF strategy, feature teams and volunteer contributor needs;
• Coaching and mentoring teammates to support continuous growth and confidence in both technical and interpersonal skills.

Qualities we are looking for:

• Clear communicator: You explain complex ideas simply and foster shared understanding across engineering, product, and non-technical audiences;
• Outcome-oriented: You prioritize work that delivers value to users and aligns with organizational goals. You balance ideal solutions with the constraints of scale, legacy, and user expectations;
• Accountable: You own your work end-to-end and help establish a culture of responsibility and follow-through;
• Candid and respectful: You offer feedback directly, constructively, and with care - and invite the same in return. You support growth by challenging ideas, not people;
• Collaborative leadership: You inspire trust and progress through support, example, and thoughtful contributions.

Requirements:

• Commitment to the Foundation's values and principles;
• Extensive experience in backend software engineering;
• Familiarity with platform or infrastructure products that serve internal or external engineering teams;
• Experience with databases and event streams, including schema design, query optimization, and efficient data access patterns;
• Deep understanding of software architecture