New

Wikidata Platform Backend Migration Specialist (Contract Position)

Remote

Summary

The Wikimedia Foundation is seeking a contract Backend Migration Specialist to join the team supporting the Wikidata Platform—the structured data backbone of Wikimedia projects and a key part of the global open knowledge ecosystem. This team is undertaking a backend migration of the Wikidata Query Service (WDQS) away from Blazegraph to a new system. This migration will remove support for several Blazegraph-specific extensions (including named subqueries, certain graph traversal patterns, geospatial services, etc) and will emphasize standards-compliant SPARQL 1.1.

This migration is necessary for the long-term sustainability of WDQS, and we expect a number of existing queries—both documented examples and community-maintained queries—will need to be reviewed, rewritten, or replaced with alternative access patterns. We are seeking a contractor to assist editors, tool authors, researchers, and other reusers with updating their queries to minimize disruptions due to the migration.

The ideal candidate will identify impacted queries, help rewrite them, document new patterns, and directly support the Wikidata community during the transition.

Important: We are a fully remote team. Your working hours will need to overlap with UTC+1 to UTC-5 time zones to accommodate members of your team around the world. Being 14:00 UTC to 17:00 UTC, the team's overlapping hours.

Duration: Mar/Apr – Oct/Nov 2026
Time commitment: 20 hours/week
Reports to: Wikidata Platform Engineering Manager

Scope of Work

You will work closely with the Wikidata Platform team and communities to support the migration through a mix of analysis, hands-on query work, documentation, and community support. This role combines judgment and execution. You help to identify issues, propose approaches, and prioritize work.

1. Query Analysis & Impact Identification

  • Review existing WDQS example queries and determine which rely on Blazegraph-specific extensions or non-SPARQL-1.1 behavior
  • Help identify classes of non-standard queries (e.g., named subqueries, named paths, geospatial queries, MediaWiki API access)
  • Inform prioritization decisions by conducting heuristic-based analysis to estimate the volume and types of affected queries (e.g., replaying Blazegraph queries against the new backend and comparing failures or result differences)
  • Surface recurring pain points or missing abstractions back to the platform team
  • Collaborate with WMF and WMDE staff on tooling or analysis approaches, where appropriate

2. Query Rewrites & Migration Support

  • Rewrite example queries shown in the WDQS UI and documentation to be compatible with the new backend
  • Develop and document canonical rewrite patterns for common Blazegraph-specific query constructs
  • Identify inconsistencies in backward compatibility, and work with our teams to document alternative approaches or data access methods
  • Community support via documented responses, office hours, and guidance in rewriting queries

3. Documentation Updates

  • Update user-facing and technical documentation to reflect the new backend, ensuring accuracy, clarity, and usefulness during and after the migration. Examples of documentation to update include:
    • Wikidata Query Service help and tutorial pages
    • WDQS user manuals and technical/implementation documentation
    • Best-practice guidance for writing performant, standards-compliant SPARQL 1.1 queries

Skills & Experience

  • Strong, hands-on experience with SPARQL, including SPARQL 1.1
  • Experience working with large or complex RDF datasets
  • Experience with data platform migrations or deprecating legacy APIs
  • Ability to understand and refactor real-world queries written by others
  • Comfort working with incomplete information and evolving technical decisions
  • Strong written communication skills, especially for technical documentation
  • Ability to work independently while coordinating with multiple stakeholders

Nice-to-Have

  • Familiarity with Wikidata, WDQS, or MediaWiki-adjacent tooling
  • Experience supporting developer or researcher communities
  • Experience designing heuristics or lightweight analysis for query usage patterns

About the Wikimedia Foundation

The Wikimedia Foundation is the nonprofit organization that operates Wikipedia and the other Wikimedia free knowledge projects. Our vision is a world in which every single human can freely share in the sum of all knowledge. We believe that everyone has the potential to contribute something to our shared knowledge, and that everyone should be able to access that knowledge freely. We host Wikipedia and the Wikimedia projects, build software experiences for reading, contributing, and sharing Wikimedia content, support the volunteer communities and partners who make Wikimedia possible, and advocate for policies that enable Wikimedia and free knowledge to thrive. 

The Wikimedia Foundation is a charitable, not-for-profit organization that relies on donations. We receive donations from millions of individuals around the world, with an average donation of about $15. We also receive donations through institutional grants and gifts. The Wikimedia Foundation is a United States 501(c)(3) tax-exempt organization with offices in San Francisco, California, USA.

As an equal opportunity employer, the Wikimedia Foundation values having a diverse workforce and continuously strives to maintain an inclusive and equitable workplace. We encourage people with a diverse range of backgrounds to apply. We do not discriminate against any person based upon their race, traits historically associated with race, religion, color, national origin, sex, pregnancy or related medical conditions, parental status, sexual orientation, gender identity, gender expression, age, status as a protected veteran, status as an individual with a disability, genetic information, or any other legally protected characteristics.

The Wikimedia Foundation is a remote-first organization with staff members including contractors based 40+ countries*. Salaries at the Wikimedia Foundation are set in a way that is competitive, equitable, and consistent with our values and culture. The anticipated annual pay range of this position for applicants based within the United States is US$70,228  to US$85,837 with multiple individualized factors, including cost of living in the location, being the determinants of the offered pay. For applicants located outside of the US, the pay range will be adjusted to the country of hire. We neither ask for nor take into consideration the salary history of applicants. The compensation for a successful applicant will be based on their skills, experience and location. 

*Please note that we are currently able to hire in the following countries: Australia, Austria, Bangladesh, Belgium, Brazil, Canada, Colombia, Costa Rica, Croatia, Czech Republic, Denmark, Egypt, Estonia, Finland, France, Germany, Ghana, Greece, India, Indonesia, Ireland, Israel, Italy, Kenya, Mexico, Netherlands, Nigeria, Peru, Poland, Singapore, South Africa, Spain, Sweden, Switzerland, Uganda, United Kingdom, United States of America and Uruguay.  Our non-US employees are hired through a local third party Employer of Record (EOR). 

We periodically review this list to streamline to ensure alignment with our hiring requirements. 

All applicants can reach out to their recruiter to understand more about the specific pay range for their location during the interview process.

If you are a qualified applicant requiring assistance or an accommodation to complete any step of the application process due to a disability, you may contact us at recruiting@wikimedia.org or +1 (415) 839-6885.

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