Senior Software Engineer

September 20, 2026

Remote

Senior

Madrid, Spain

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Description

The Wikimedia Foundation is hiring a Senior Software Engineer for its MediaWiki Content Platform team to evolve wikitext, the markup language behind Wikipedia. The role involves designing and delivering improvements to wikitext processing infrastructure, writing PHP and JavaScript, and building and maintaining APIs and content rendering and transformation services used by hundreds of world languages. It is a fully-remote, open-source position with occasional travel and a preferred timezone for the candidate of GMT-4 to GMT+2. The role emphasizes strong engineering practices, mentoring other engineers, and collaboration across team and organizational boundaries.

Responsibilities

Designing and delivering improvements to Wikipedia's wikitext processing infrastructure, balancing user experience, performance, backwards compatibility, and maintainability
Iterating on new features through collaboration with fellow engineers, product managers, designers, client teams, and community members
Writing PHP and JavaScript which supports hundreds of world languages
Creating and maintaining internet APIs with server scripting languages
Instrumenting components to monitor feature and quality characteristics
Leveraging caching and persistence technologies

Requirements

5+ years of related professional experience in software engineering
Experience with one or more of: parser generators, interpreters, language runtimes, compilers, or bringing a language feature through a product cycle
Demonstrated ability to own complex technical projects from problem definition through implementation and delivery, including making and communicating architectural decisions and navigating ambiguity
Experience designing and maintaining reliable, performant software components used by other teams, products, or large numbers of users
Strong engineering practices: writing unit and integration tests, proactively addressing security and code review feedback, and balancing architectural tradeoffs
Ability to work effectively across team and organizational boundaries, identify and resolve technical dependencies, and bring projects to completion with limited direction
Experience mentoring other engineers and raising the technical quality of a team through code reviews, design discussions, documentation, or direct mentorship
A desire to make meaningful contributions to knowledge equity, free culture, and open access
An emphasis on communicating clearly in both synchronous and asynchronous channels
Self motivated with an ability to navigate through ambiguity and bring a project to completion with limited direction
Familiarity with the HTML5 spec and DOM manipulation
Expertise in Node.js and related technologies
Familiarity with Wikipedia, wikitext or markdown editing, or content management systems such as MediaWiki, Drupal or WordPress
A history of open source contribution
Bachelor's, master's, or doctorate degree in computer science, software engineering, or other STEM field, or equivalent certification

Conditions

Fully-remote environment with occasional travel for team, department, or organization events
Preferred timezone for the candidate is GMT-4 to GMT+2
Remote-first organization with staff and contractors based in 40+ countries
Non-US employees are hired through a local third party Employer of Record (EOR)
For US-based applicants the position is part of the Communication Workers of America bargaining unit
Consensus-oriented team culture with a stated emphasis on work-life balance

PHPJavaScriptNode.jsHTML5DOMMySQLMediaWikiWikitextMarkdownParser generatorsCompilersInternet APIsCachingPersistencenonprofit / open knowledge / internet encyclopediaMentoring engineersCode reviewDesign discussions

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