7 min read
2026-02-20
JSON (JavaScript Object Notation) is a text-based data interchange format based on JavaScript. It is used in virtually every web application for transferring data between client and server.
Minified JSON saves bandwidth but is impossible to read:
{"name":"Ivan","age":25,"skills":["JS","Python"],"address":{"city":"Moscow"}}Formatted JSON is easy to read and debug:
{
"name": "Ivan",
"age": 25,
"skills": ["JS", "Python"],
"address": {
"city": "Moscow"
}
}Paste JSON into the input field
Click "Format"
Get indented, readable JSON
Removes all whitespace and line breaks to reduce size.
Checks JSON correctness and shows errors with line numbers.
| Error | Example | Fix |
|---|---|---|
| Trailing comma | {"a": 1,} | {"a": 1} |
| Single quotes | {'a': 1} | {"a": 1} |
| Unquoted keys | {a: 1} | {"a": 1} |
| Trailing comma | [1, 2, 3,] | [1, 2, 3] |
See also: Regex Tester, Base64 Encoder, Case Converter