Senior Software Engineer - MediaWiki Interfaces

Summary

The Wikimedia Foundation is seeking a Senior Software Engineer to join the MediaWiki Interfaces team. MediaWiki, the open-source platform powering Wikipedia and its sister projects, impacts hundreds of millions of users globally. Our team is responsible for the web API and other integration interfaces of MediaWiki, enabling efficient and reliable access, editing, and consumption of knowledge.

This role offers a unique opportunity to combine technical depth with mission-driven impact. As a Senior Engineer, you will write robust code, lead by example, prioritize high-impact work, foster a culture of accountability, transparency, and continuous improvement, and support better decision-making through metrics and observability.

Important: This is a fully remote position. Your working hours must overlap with UTC+2 to UTC-7 time zones to accommodate global team members.

Responsibilities

• Design, develop, and maintain key parts of the MediaWiki stack.
• Drive technical quality and operational excellence by defining and reinforcing standards in testing, observability, and system reliability.
• Autonomously create proofs of concept, write design documents, and break down complex projects into actionable tasks to support less experienced team members.
• Contribute to the adoption and advocacy of API-first development, influencing best practices in system design, SLOs/SLAs, and OpenAPI Specification.
• Champion product metrics: ensure key user journeys are instrumented and monitored to guide decisions and evaluate success.
• Lead by example in code review, decision-making, and team culture, fostering transparency, empathy, and collaboration.
• Improve and automate processes for identifying, tracking, and resolving production issues.
• Collaborate with the Product team and the community to ensure technical solutions align with user and contributor needs.
• Coach and mentor teammates to support continuous growth and confidence in both technical and interpersonal skills.

Qualities We Are Looking For

• Clear communicator: Ability to explain complex ideas simply and foster shared understanding across engineering, product, and non-technical audiences.
• Outcome-oriented: Prioritize work that delivers value to users and aligns with organizational goals, balancing ideal solutions with constraints.
• Accountable: Own work end-to-end and help establish a culture of responsibility and follow-through.
• Candid and respectful: Offer feedback directly, constructively, and with care, inviting the same in return. Support growth by challenging ideas, not people.
• Collaborative leadership: 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.