Which NetCDF formats are supported?

Binary NetCDF classic (CDF-1), CDF-2 (64-bit offsets), CDF-5 (large-format), and NetCDF-4 files backed by HDF5, plus JSON documents and JSON exports of NetCDF data. Files up to 40 MB.

Does this return every data value?

For classic files you get the full contents of fixed-size variables and the first record of record variables; for NetCDF-4/HDF5 files a container summary is returned unless the netCDF4 library is available, in which case variables are listed too. Very large arrays are sampled to the first 128 values with a flag when truncated.

What if my file is not NetCDF?

The tool inspects the first bytes and reports what it found instead of guessing. Non-NetCDF files get a small probe report; high-entropy random content is rejected.

Convert NetCDF data files to JSON online

Have a scientific data file that will not open in a spreadsheet or a text editor? This page reads a NetCDF data file and returns a structured JSON report of its contents that you can search, copy, or feed into other tools.

NetCDF (Network Common Data Form) is the standard format for array-oriented scientific data — climate model output, ocean and atmosphere observations, satellite retrievals. A NetCDF file organizes data into:

Dimensions — named axes such as time, lat, and lon, with lengths
Variables — typed data arrays with any number of dimensions
Attributes — metadata describing the file and its variables

This converter reads those structures and produces a single JSON report you can download.

What you get

A JSON report containing:

The detected format (classic CDF-1, CDF-2, CDF-5, or NetCDF-4/HDF5)
Every dimension with its length and whether it is an unlimited record dimension
Every global attribute and variable attribute with typed values
Every variable with its type, shape, dimensions, and values
The record count and record variables of the file

Record variables (those using an unlimited dimension) report the first record plus their full shape, and very large arrays are sampled to the first 128 values. Anything sampled or truncated is marked with a flag so the report stays honest about what it contains.

How to convert

Upload a NetCDF file up to 40 MB (.nc, .cdf, .nc4), or a JSON export of NetCDF data.
Press Convert file.
Download the JSON report — or copy it into a script, notebook, or documentation.

When this helps

Peeking into a model output or observation file before writing analysis code
Checking variable names, units, and dimensions without installing h5py or netCDF4
Extracting metadata for data papers or catalogs
Quick sanity checks on a NetCDF file you just downloaded

Verified sample files

The module ships genuine files written by libnetcdf and pins them for authoritative QA through verification.fixtures. The recipe tests run the real reader on each one:

Sample	QA mode	Container	Expected result
`fixtures/classic.cdf`	happy	NetCDF classic (CDF-1, 32-bit offsets)	`status: "parsed"`, dimensions, attributes and values
`fixtures/cdf2-offsets.nc`	boundary	CDF-2 (64-bit offsets)	`status: "parsed"`, `format.id: "netcdf-cdf-2"`
`fixtures/noise.bin`	hostile	high-entropy random bytes	non-zero exit with a clean `error:` diagnostic and no report file

Additional genuine samples covering CDF-5 and NetCDF-4 (cdf5.nc, netcdf4.nc, netcdf4-classic.nc) are exercised by the module tests.

Files that are not NetCDF are not faked into a success: a recognized foreign format (a PNG, a ZIP, a FITS file) returns a probe report naming what it found, and content with no structure at all — high-entropy random bytes — is refused with an explicit error rather than a made-up report.

Related scientific data tools

Once you know what is inside a NetCDF file, these adjacent operations may help:

Extract embedded images from NetCDF — pull out PNG/JPEG previews stored in attributes or variables
Convert HDF5 (.h5) to JSON — inspect structured HDF5 tables
Convert FITS to JSON — read telescope/lab FITS headers
Convert mzML to PNG — preview mass-spectrometry runs

Browse all NetCDF and scientific data tools.