CMR (Common Metadata Repository)

NASA’s master catalog. Every Earth-observation collection and granule is indexed here, searchable via a REST API.

Why it matters

CMR is the engine behind Earthdata Search, Worldview, and most NASA data tools. When you search NASA data, you’re querying CMR — directly or indirectly.

Where you’ll meet it

• Every Explore catalog search and the AOI (area-of-interest) widgets in this atlas query CMR under the hood to find matching collections and granules.
• The earthaccess Python library wraps CMR — earthaccess.search_data(...) is a CMR granule query, returning the download links it hands back.
• Finding MODIS, GPM, or SMAP files by bounding box and date range is a CMR call; the DAAC that owns the data is named in the result, but the search is one shared endpoint.
• Earthdata Search and Worldview’s “add data” panels are front-ends over the same CMR API.

In plain terms

The card catalog for all of NASA’s Earth data — 18,000+ collections, billions of granules, one search endpoint.