What is JSON — data format explained
What is JSON: a text format for objects and arrays used in APIs and configs, plus an online validator.
JSON (JavaScript Object Notation) is a text data format built on “key: value” pairs. It supports objects in curly braces, arrays in square brackets, double-quoted strings, numbers, booleans, and null. The format is language-independent.
The syntax is strict: keys must be quoted, no trailing commas, no leading zeros in numbers. Even a small mistake makes the document invalid — so it's worth validating JSON with a formatter before sending or pasting it into a config.
JSON is used almost everywhere: API responses, configuration, state storage, and service-to-service exchange. In ToolsHelper you can pretty-print or minify JSON, sort keys, and find the exact syntax error position.
JSON is objects, arrays, strings, numbers, true, false, and null. Strings use double quotes. A trailing comma is a syntax error. Numbers cannot have a leading zero. Comments are not allowed, even though many configs look like JSON and are not. This page is the definition. Pretty-print and minify of a payload you paste is the converter.
FAQ
JSON vs JS object?
Similar, but JSON is stricter and has no functions.
Why are trailing commas not allowed?
The ECMA-404 standard forbids them — parsers treat the document as invalid.