What is JSON?

JSON (JavaScript Object Notation) is a lightweight text format for structured data. It is easy for both people and programs to read and write, which is why APIs, config files, and logs often use it.

What JSON looks like

Objects use curly braces and string keys in double quotes. Arrays use square brackets. Strings must use double quotes (not single quotes). Common value types are strings, numbers, booleans, null, arrays, and nested objects.

{
  "name": "LocalTools",
  "private": true,
  "tags": ["json", "privacy"]
}

Why JSON matters

Most web APIs return JSON. Many tools and CLIs emit JSON so scripts can parse output reliably. When something goes wrong, the first step is often to validate that the text is valid JSON (matching braces, commas only between values, and so on).

Try it locally in your browser

If you need to format, minify, or validate JSON without sending it to a server, use the JSON Formatter & Validator on LocalTools. Your paste stays in your browser.

Related ideas

• JSON vs YAML: YAML is often used for config; JSON is stricter and ubiquitous on the wire. The site’s JSON ↔ YAML converter can help compare shapes.
• JSONPath: See What is JSONPath? for the query language, then try the JSONPath evaluator.