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Data file

What is a .cdf file?

A .cdf file is a netCDF-3 Classic. This is a data file — structured information used by a program rather than read directly. Confusingly, this extension has been used by 5 different formats over the years — they're all listed below.

This extension has been used by more than one format

5 different formats have claimed .cdf over the years, so two files with the same extension aren't necessarily the same kind of thing.

How to open a .cdf file

  • Start with the program that produced it; that's almost always the right tool.
  • Open it in a text editor to see whether it's readable text or binary.
  • For database formats, DB Browser for SQLite or LibreOffice Base can often import it.

The registry records this extension against netCDF-3 Classic, netCDF-3 64-bit, Common Data Format dotCDF and others, so software from that family is the most likely match.

How to convert a .cdf file

  • If you can view the data, exporting to .csv is usually the most portable option.

MIME type

When a .cdf file travels over the web, servers label it with one of these MIME types:

application/netcdfapplication/x-netcdf

What's a MIME type?

The technical record

For archivists, developers and the merely curious: these are the PRONOM registry entries for .cdf.

Format nameVersionMIME typePUID
netCDF-3 Classicapplication/netcdf, application/x-netcdffmt/282
netCDF-3 64-bitapplication/netcdf, application/x-netcdffmt/283
Common Data Format dotCDF2.0-2.5fmt/1948
Common Data Format dotCDF2.6-2.7fmt/1949
Common Data Format dotCDF3.xfmt/1950

Got another one?