What is a .json file? (JSON)

JSON is the most common format for exchanging structured data between programs and web APIs. It is plain text made of key-value pairs and lists, easy for both humans and machines to read, which is why it powers most modern web services.

What is a .json file used for?

JSON represents data as objects (key-value pairs in braces) and arrays (lists in brackets). It is concise, unambiguous and maps neatly onto the data structures of nearly every programming language.

It replaced XML for most web APIs because it is lighter and easier to read. Config files, app settings and API responses are frequently JSON.

Being plain text, a JSON file opens in any editor. Formatting it with indentation, known as pretty-printing, makes large files far easier to scan.

How to open a .json file

The .json format opens in the following apps, grouped by operating system. If one app does not work, try another from the same list. For a step-by-step walkthrough, see how to open a .json file.

Windows

Notepad++
VS Code
any text editor

macOS

VS Code
TextEdit
any editor

Linux

VS Code
nano
any editor

Web

Browsers show raw JSON; dev tools format it

How to convert a .json file

You can convert a .json file to CSV, XML, YAML using a conversion tool or the export menu of an app that opens it.

.json file signature (magic bytes)

Programs recognise a .json file by the bytes at the start of the file, not by its name. These are the signatures for JSON.

Hex signature	Offset	Note
7B	0	'{' object (usually)
5B	0	'[' array

See the full magic-numbers reference for every format.

Frequently asked questions