Job Summary

The [Employer hidden — sign up to reveal] 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. This role offers a unique opportunity to combine technical depth with mission-driven impact.

Responsibilities

• 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 decisions and 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

Requirements

• Commitment to the Foundation's Mission and Values
• 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, testing methodologies, and system design
• Strong experience in observability practices: setting up metrics, logging, monitoring, and alerting
• Familiarity with incident response, root cause analysis, and follow-up processes
• Experience working with CI/CD pipelines and automated test infrastructure

Preferred Qualifications

• Experience developing frameworks (designing for reuse, extensibility, stability, and backward compatibility)
• Proficiency in PHP and JavaScript
• Familiarity with identity management, including OAuth
• Experience with Kubernetes ecosystem, including Envoy
• Experience with Prometheus and Grafana
• Experience defining and working with SLAs/SLOs or other production reliability frameworks
• Prior experience with MediaWiki or Wikimedia projects
• Contributions to open-source software
• Experience working in a fully remote, distributed team

About [Employer hidden — sign up to reveal]

The [Employer hidden — sign up to reveal] is the nonprofit organization that operates Wikipedia and the other Wikimedia free knowledge projects. Our vision is a world in which every single human can freely share in the sum of all knowledge. We believe that everyone has the potential to contribute something to our shared knowledge, and that everyone should be able to access that knowledge freely. We host Wikipedia and the Wikimedia projects, build software experiences for reading, contributing, and sharing Wikimedia content, support the volunteer communities and partners who make Wikimedia possible, and advocate for policies that enable Wikimedia and free knowledge to thrive. The [Employer hidden — sign up to reveal] is a charitable, not-for-profit organization that relies on donations. We receive donations from millions of individuals around the world, with an average donation of about $15. We also receive donations through institutional grants and gifts. The [Employer hidden — sign up to reveal] is a United States 501(c)(3) tax-exempt organization with offices in San Francisco, California, USA. As an equal opportunity employer, the [Employer hidden — sign up to reveal] values having a diverse workforce and continuously strives to maintain an inclusive and equitable workplace.