Senior Software Engineer - MediaWiki Interfaces

Summary

The Wikimedia Foundation is seeking a Senior Software Engineer to join the MediaWiki Interfaces team. MediaWiki is the open-source platform powering Wikipedia and its sister projects, impacting 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, support data-driven decision-making through metrics and observability, and foster a culture of accountability, transparency, and continuous improvement.

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

• 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.
• 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, influencing best practices in system design, SLOs/SLAs, and OpenAPI Specification.
• Championing product metrics: ensuring 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: Explains complex ideas simply and fosters shared understanding across engineering, product, and non-technical audiences.
• Outcome-oriented: Prioritizes work that delivers value to users and aligns with organizational goals, balancing ideal solutions with constraints.
• Accountable: Owns work end-to-end and helps establish a culture of responsibility and follow-through.
• Candid and respectful: Offers feedback directly, constructively, and with care, inviting the same in return. Supports growth by challenging ideas, not people.
• Collaborative leadership: Inspires 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.