How to use the JSON formatter
Paste JSON into the input box. Choose Format with indentation to make nested data readable, or Minify JSON to remove unnecessary whitespace for compact storage or transport.
The result updates in the browser. If the JSON is malformed, the workspace keeps your input visible and shows a recoverable error instead of clearing the editor.
JSON is stricter than a JavaScript object literal
Valid JSON requires double-quoted property names and string values. Comments, trailing commas, single-quoted strings, undefined, functions, and bare JavaScript identifiers are not JSON. A snippet that works inside JavaScript source can therefore fail JSON parsing.
For example, this is valid JSON:
{ "name": "MyTool0", "enabled": true, "tags": ["text", "image"] }But {name: 'MyTool0',} is a JavaScript-style object literal, not valid JSON.
What this tool checks
- Valid JSON syntax accepted by the browser parser.
- Top-level value type, such as object, array, string, number, boolean, or null.
- Top-level object key count for quick inspection.
- UTF-8 byte count for the pasted JSON text.
This tool does not run JSONPath, execute code, fetch remote URLs, or validate JSON Schema. It is meant for quick formatting and syntax checks.
Important numeric precision limit
The current formatter uses the browser’s standard JSON.parse and JSON.stringify behavior. JSON numbers are therefore represented as JavaScript Number values. Integers beyond JavaScript’s safe integer range, and some high-precision numeric values, can lose precision when parsed and then serialized.
That matters when an identifier is encoded as a JSON number instead of a string. If exact digit preservation is required for very large integers, do not rely on a standard JavaScript parse/stringify round trip; use a lossless JSON workflow or encode identifiers as strings when the data format allows it.
This warning should be revisited if the formatter implementation is replaced with a lossless number parser in a later branch.
Troubleshooting parse errors
Check the first structural mismatch rather than repeatedly adding braces at the end. Common causes include a trailing comma, a missing comma between properties, unescaped quotation marks inside a string, or extra text after the final JSON value. Minifying cannot repair invalid syntax; fix the input first.
Privacy and limits
The JSON stays in the current browser tab. MyTool0 does not upload the pasted value for formatting. Very large JSON payloads can still consume substantial memory and block a browser while parsing. If a file is too large to paste comfortably, use a local editor or command-line parser designed for that workload.
For the distinction between local processing and ordinary page requests, see What browser-local file processing means.