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JSON (/?d?e?s?n/ jay-s?n),^[1] or JavaScript Object Notation, is an open standard format that uses human-readable text to transmit data objects consisting of attribute–value pairs. It is used primarily to transmit data between a server and web application, as an alternative to XML.

Although originally derived from the JavaScript scripting language, JSON is a language-independent data format. Code for parsing and generating JSON data is readily available in a large variety of programming languages.

The JSON format was originally specified by Douglas Crockford. It is currently described by two competing standards, RFC 7159 and ECMA-404. The ECMA standard is minimal, describing only the allowed grammar syntax, whereas the RFC also provides some semantic and security considerations.^[2] The officialInternet media type for JSON is application/json. The JSON filename extension is .json.

JSON's basic types are:

• Number — a signed decimal number that may contain a fractional part and may use exponential E notation. JSON does not allow non-numbers like NaN, nor does it make any distinction between integer and floating-point. (Even though JavaScript uses a double-precision floating-point format for all its numeric values, other languages implementing JSON may encode numbers differently)
• String — a sequence of zero or more Unicode characters, though characters outside the BMP must be represented as a surrogate pair. Strings are delimited with double-quotation marks and support a backslash escaping syntax.
• Boolean — either of the values true or false
• Array — an ordered list of zero or more values, each of which may be of any type. Arrays use square bracket notation with elements being comma-separated.
• Object — an unordered associative array (name/value pairs). Objects are delimited with curly brackets and use commas to separate each pair, while within each pair the colon ':' character separates the key or name from its value. All keys must be strings and should be distinct from each other within that object.
• null — An empty value, using the word null

JSON generally ignores any whitespace around or between syntactic elements (values and punctuation, but not within a string value). However JSON only recognizes four specific whitespace characters: the space, horizontal tab, line feed, and carriage return. JSON does not provide or allow any sort of comment syntax.

Early versions of JSON (such as specified by RFC 4627) required that a valid JSON "document" must consist of only an object or an array type—though they could contain other types within them. This restriction was relaxed starting with RFC 7158, so that a JSON document may consist entirely of any possible JSON typed value.

The following example shows a possible JSON representation describing a person.

{ "firstName": "John", "lastName": "Smith", "isAlive": true, "age": 25, "height_cm": 167.6, "address": { "streetAddress": "21 2nd Street", "city": "New York", "state": "NY", "postalCode": "10021-3100" }, "phoneNumbers": [ { "type": "home", "number": "212 555-1234" }, { "type": "office", "number": "646 555-4567" } ], "children": [], "spouse": null }