YouthMappers Validation Hub
Building better maps — and better mappers — through quality data.
WHAT IS VALIDATION AND WHY DOES IT MATTER?
Every feature mapped on OpenStreetMap — a building, a road, a health clinic — is only as useful as it is accurate. Validation is the quality control step that makes sure mapped data is correct, complete, and tagged properly before it gets used by humanitarian responders, urban planners, and communities around the world.
When you validate, you're not just checking someone else's work. You're closing the loop on the entire mapping process — turning raw contributions into reliable data that people depend on.
We look for three things:
1. Spatial accuracy — Are features traced correctly? Are buildings squared? Are roads properly connected?
2. Tagging accuracy — Are features labeled with the right OSM tags?
3. Completeness — Are all required features mapped according to the project instructions?
A brief history
The YouthMappers Validation Hub was launched in June 2019 by faculty and students at The George Washington University in Washington, D.C. It was formed with a clear purpose: to ensure that data produced by YouthMappers chapters met the highest standard of quality in OpenStreetMap.
The original hub developed training materials in English, French, and Spanish; hosted validation parties and training sessions; pioneered interactive validation workflows using JOSM and OSMCha; and validated dozens of HOT Tasking Manager projects across the YouthMappers network. That foundation — the tools, training materials, and workflows they built — continues to guide the program today.
YouthMappers' validation efforts are now supported by our Volunteer Regional Ambassador Validation Team — experienced mappers around the world who lead JOSM and validation trainings, support data quality in their regions, and are available to help.
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Attendees of the Hub’s #ValidationFriday event posing with The George Washington University Geography alien mascot, Geoid.
LEARN TO VALIDATE
Whether you're new to OSM or an experienced mapper ready to level up, these resources will walk you through everything you need to get started with validation. Work through these resources in order to build your skills step by step.
Step 1: Learn JOSM
JOSM is the advanced editing software used by validators across the YouthMappers network. Start here before moving on to validation.
Step 2: Learn to Validate
Once you're comfortable in JOSM, you're ready to start validating. These resources will walk you through the full validation workflow.
Explore the full list of JOSM resources on the YouthMappers Resource Library.
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🎓 Advanced JOSM Techniques & Validation — YouthMappers Academy Course
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📄 YouthMappers Validation Training Document (also available in español and français)
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⚡Validation Messages (also available in français)
Explore the full list of Validation resources on the YouthMappers Resource Library.