Senior Software Engineer

Senior Software Engineer - MediaWiki Interfaces

Summary

The Wikimedia Foundation is looking for a Senior Software Engineer to join the MediaWiki Interfaces team. MediaWiki is the open-source platform that powers Wikipedia and its sister projects - impacting hundreds of millions of Wikipedia users across the globe. Our team owns the web API and other integration interfaces of MediaWiki, enabling other teams to create features that allows users to access, edit, and consume knowledge efficiently and reliably. The MediaWiki Product Insights have more information on the kind of work the group undertakes.

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.

Important: We are a fully remote team. Your working hours will need to overlap with UTC+2 to UTC-7 time zones to accommodate members of your team around the world.

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.

Abo