noun

JSON

JAY-son

JSON (noun) means a plain-text format for storing and sending structured data, using labelled values grouped inside braces and lists inside square brackets. It is readable by people and easily processed by most programming languages. Example: “The API returns the whole order history as JSON.”

noun

technical A plain-text format for storing and sending structured data, using labelled values grouped inside braces and lists inside square brackets. It is readable by people and easily processed by most programming languages.

"The API returns the whole order history as JSON."

"Open the config file and you will see a few dozen lines of JSON."

How to Use JSON

Learner’s notes

In plain EnglishJSON is a simple text way of writing down data so programs can pass it around.

When to use it

Pronounced like the name Jason. Used as an uncountable noun and as a modifier: "a JSON file", "parse the JSON".

Memory tip

JSON borrowed its syntax from JavaScript but is not JavaScript and is not tied to it — nearly every language can read and write it.

Trace the full origin ↓

Easily confused with

JavaScript → XML → YAML → CSV →

Common pairings

JSON file parse JSON valid JSON JSON payload return JSON

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Fill the Gap

Can you complete this real example?

The API returns the whole order history as _____.

Etymology

An initialism of JavaScript Object Notation, from the fact that its syntax follows the way objects are written in JavaScript.

Origin: English

Synonyms

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JavaScript Object Notation data-interchange format

Rhymes for JSON

son

See all rhymes for JSON →

Frequently Asked Questions

What is the difference between JSON and XML?

Both carry structured data as text. JSON is lighter, with less punctuation, and maps directly onto the lists and key-value structures most languages already have. XML is more verbose but supports features JSON lacks, such as attributes, namespaces and schema validation, and is still common in older enterprise systems.

Is JSON the same as JavaScript?

No. JSON is a data format whose syntax was taken from JavaScript's way of writing objects. It contains data only — no functions, no logic — and is used by languages far beyond JavaScript.

What does it mean when JSON is "invalid"?

The text does not follow the format's rules — commonly a missing comma or bracket, a trailing comma, or single quotes where double quotes are required. Parsers reject the whole document rather than guessing, so one small error stops the entire file being read.