Senior Software Engineer - MediaWiki Interfaces at Wikimedia Foundation

You will be responsible for:

• Designing, developing, 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;
• Contributing to the adoption and advocacy of API-first development, and influencing best practices in system design, SLOs/SLAs, and OpenAPI Specification;
• Championing product metrics: ensuring that key user journeys are instrumented and monitored to 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 user and 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 Mission and Values;
• Extensive experience in software engineering, ideally in high-impact web platforms and/or open-source;
• Good understanding of HTTP;
• Proficiency in PHP and JavaScript; 
• 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;

Additionally, we’d love it if you have:

• Experience developing frameworks (designing for reuse, extensibility, stability, and backward compatibility);
• 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 with developer experience tooling, public APIs, or platform teams;
• Experience working in a remote, distributed team.