- Mass GIS
- City of Boston
- Metro Boston Data Common
- US Federal Government
- US Geological Survey
- USGS National Map Viewer
- USGS National Map Services
- Wikipedia GIS Data Resources
- Free GIS Data Sources
- Facebook Data for Good
- The International Monitoring System includes seismic, hydroacoustic, infrasound and radionuclide data compiled on global scale.
- iNaturalist contains crowdsourced observations of plants and animal species, available for download with free subscription.
- Global Administrative Data (GADM) downloadable by country.
- Global Open Data for Agriculture and Nutrition
- Humanitarian Data Exchange
See also some curated lists of GIS data at these websites:
UPENN Library Guide to GIS Data