Developer tools / JSON

Make JSON easier to read.

Check JSON syntax, format valid data with consistent indentation, and see a readable message when parsing fails.

How this tool works

Private by design
Validation and formatting happen in this browser. Your JSON is not sent to a server.

Free online tool

JSON formatter and validator

Paste JSON or start with the example.

0 characters
Tip: press Ctrl + Enter (or Cmd + Enter) to format.
Ready when you are.
Only JSON syntax is checked; no schema or application rules are evaluated.

A small guide

Valid JSON is easier to inspect.

Consistent indentation makes nested objects and arrays easier to scan. A readable parse error can help locate syntax mistakes without sending your data anywhere.

What this tool checks

The browser's JSON parser checks whether the input follows JSON syntax. If it is valid, the tool prints the parsed value with your chosen indentation. If parsing fails, the message includes a line and column when the browser provides a source position.

Before

{"name":"Ada","topics":["SQL","JSON"],"active":true}

After

{
  "name": "Ada",
  "topics": [
    "SQL",
    "JSON"
  ],
  "active": true
}

What it does not check

Syntactically valid JSON may still be wrong for your application. This tool does not validate a JSON Schema, check required fields, confirm API compatibility, or verify that values are safe for your application. Parsing and re-serializing can normalize number spellings and retain only the last occurrence of a duplicate object key. Review the output before using it.

Continue learning

See common JSON syntax errors for before-and-after examples, or explore the other developer tools.

Is my JSON uploaded or stored?

No. Parsing and formatting happen locally in your browser. This tool does not submit your JSON to TeachyLeaf.

Does valid JSON mean my data is correct?

No. A successful parse confirms JSON syntax only. It does not check your application's schema, business rules, or API requirements.

Why can error messages differ between browsers?

Browsers use different JSON parser implementations. When a parser reports a source position, this tool converts it to a line and column; otherwise it shows the browser's parse message.