How to use JSON formatter
- Paste JSON from an API response, configuration file, or a test fixture. Use invented values when trying a sample.
- Select Convert. Invalid syntax, duplicate field names, and unsafe integer values produce an error.
- Review the formatted object or array. Copy the output or download it as text.
Make a JSON value readable
This formatter parses JSON and serializes the result with two spaces per indentation level. It accepts objects, arrays, strings, numbers, booleans, and null at the root. It does not execute code, make an API request, or turn JavaScript object syntax into JSON.
Comments, trailing commas, single-quoted strings, and unquoted keys are not valid JSON for this tool. Keep a copy of the original when comparing exact bytes: indentation, numeric spelling, escape sequences, and object key ordering may change during parsing and serialization.
Precision and supported input
Input is limited to 200,000 UTF-16 units and 30 nested container levels. Duplicate object field names are rejected instead of keeping only the last occurrence. Non-finite numbers and parsed integer values outside JavaScript's safe integer range are also rejected.
Decimal precision follows JavaScript Number. A formatter does not establish that an API response is correct or that a value fits your application's schema. Represent exact financial decimals or very large identifiers as strings when that is your data contract.
Processing happens in this page
The conversion function runs in your browser and sends no input to a conversion server. It has no account requirement or conversion history. Clipboard and download controls act on the displayed output; browser extensions and normal page-hosting requests are outside that conversion function.
Which format do you need?
| Your next task | Input or choice | Output or result |
|---|---|---|
| Read a compact API response | Compact JSON may be hard to scan. | Two-space indentation makes nesting visible. |
| Preserve exact original bytes | Retain the original file or response. | Parsing and serialization can change representation. |
| Check an application's schema | Requires the actual schema and rules. | Formatting only checks supported JSON syntax and numeric bounds. |
Questions about this tool
Does it accept JSON comments?
No. Comments, trailing commas, and single-quoted strings are rejected.
Will it preserve every number exactly?
Decimal precision follows JavaScript Number. Unsafe integer and non-finite values are rejected. Use string fields when your contract needs exact large identifiers or decimal representations.
Why are duplicate keys rejected?
Parsing duplicate keys would normally keep the last value. This formatter rejects them to avoid silently discarding a value.
Is my JSON uploaded?
The formatting code processes input in this browser page and sends no input to a conversion server. There is no saved conversion history.
What is the input limit?
The converter accepts at most 200,000 UTF-16 units and 30 nested object or array levels.