Senior Software Engineer, MediaWiki

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.

• 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.

• 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.

• 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.

• 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.

The Wikimedia Foundation 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 Wikimedia Foundation 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 Wikimedia Foundation is a United States 501(c)(3) tax-exempt organization with offices in San Francisco, California, USA.

As an equal opportunity employer, the Wikimedia Foundation values having a diverse workforce and continuously strives to maintain an inclusive and equitable workplace. We encourage people with a diverse range of backgrounds to apply. We do not discriminate against any person based upon their race, traits historically associated with race, religion, color, national origin, sex, pregnancy or related medical conditions, parental status, sexual orientation, gender identity, gender expression, age, status as a protected veteran, status as an individual with a disability, genetic information, or any other legally protected characteristics.

The Wikimedia Foundation is a remote-first organization with staff members including contractors based 40+ countries*. Salaries at the Wikimedia Foundation are set in a way that is competitive, equitable, and consistent with our values and culture. The anticipated annual pay range of this position for applicants based within the United States is US$113,082  to US$175,725  with multiple individualized factors, including cost of living in the location, being the determinants of the offered pay. For applicants located outside of the US, the pay range will be adjusted to the country of hire. We neither ask for nor take into consideration the salary history of applicants. The compensation for a successful applicant will be based on their skills, experience and location.

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