NetCDF-Java Library

The NetCDF-Java Library is a Java interface to NetCDF files, as well as to many other types of scientific data formats. 

The library is freely available and the source code is released under the (MIT-style) NetCDF C library license. Previous versions use the GNU Lesser General Public License (LGPL).

The preferred place to ask questions, discuss problems and features and get support is in the NetCDF-Java email list, which you can subscribe to from this page. Also you might want to search or browse previous netCDF-Java support questions.


The NetCDF-Java library implements a Common Data Model (CDM), a generalization of the NetCDF, OpenDAP and HDF5 data models. The library is a prototype for the NetCDF-4 project, which provides a C language API for the "data access layer" of the CDM, on top of the HDF5 file format. The NetCDF-Java library is a 100% Java framework for reading netCDF and other file formats into the CDM, as well as writing to the netCDF-3 file format. Writing to the netCDF-4 file format requires installing the netCDF C library. The NetCDF-Java library also implements NcML, which allows you to add metadata to CDM datasets, as well as to create virtual datasets through aggregation. The THREDDS Data Server (TDS) is built on top of the NetCDF-Java library.

CDM/TDS source is hosted on GitHub. To build the latest stable version from source or contribute code to the THREDDS project, see here. Most projects use netcdfAll.jar or toolsUI.jar (see below for links), or include the desired artifacts in their maven or gradle builds. See Build Dependencies for details.

Unidata CDM/THREDDS Software Engineering tools:

Current stable release version 5 (requires Java 8)

Current maintenance release version 4.6 (requires Java 8)

File format types

The NetCDF-Java library can read various file types and remote access protocols.

Notes to GRIB users:

Caveats and not-so-stable APIs:

Related Documents:

CF Conventions

Coordinate Systems

Working notes and documentation on the coordinate system layer of the CDM

Feature Types

Working notes and documents on the scientific feature type layer of the CDM

Streaming NetCDF (Experimental)


Miscellaneous Resources

Software libraries used by the Netcdf-Java library:

Additional software libraries used by ToolsUI:

Applications using the Netcdf-Java library (partial list):

This document was last updated November 2018