JSON formatter validator

What is this tool?

Check JSON syntax and make valid JSON easier to inspect. Pretty printing adds indentation; minifying removes unnecessary presentation whitespace. Neither operation decides whether the data is correct for a particular API or application.

How to use it

1. Read the input labels and limits below, then choose the operation that matches your task.
2. Paste the JSON document into the input.
3. Choose Format or Minify and inspect any parsing error.
4. Review the output before copying it into another system.
5. Check the result against the worked example or original file before copying, downloading or using it elsewhere.

Worked example

The object {"active":true} is valid JSON, while {active:true} is not because its property name lacks double quotes. A valid object can still be rejected by an API if required fields or allowed values are missing.

Questions & limits

How to use json formatter

Paste a JSON document and choose Format for two-space indentation or Minify for compact output. Validation uses the browser’s JSON parser, so comments, trailing commas and single-quoted keys are rejected. On error, the original input stays available.

A practical example

The input {"name":"Alex","active":true} is valid JSON. The input {name: "Alex"} is not: object keys must use double quotes.

Know the limits

JavaScript parsing can round integers beyond 9,007,199,254,740,991. Duplicate object keys keep the last value. Never use this formatter as a lossless editor for large financial identifiers.

Tool documentation updated October 4, 2026.

Why is my JSON rejected?

JSON requires double-quoted property names and strings. Remove comments and trailing commas, then check the error message. Formatting changes presentation; it does not validate your application’s data schema.

Is formatting always lossless?

No. Parsing can affect duplicate keys and large numeric values. Keep identifiers as strings where the data contract permits, and preserve the source when exact representation matters.

Check the receiving system

Use a small known example first when connecting this result to an application. Encoding, formatting and color conversion each follow specific conventions, and the receiving system must expect the same convention. Keep an unchanged copy of important input before transforming it. Review identifiers and punctuation carefully rather than relying only on whether the operation completed. This page runs a focused utility; it does not validate the full behavior, security or business rules of the application where you will use the output.