What does 'invalid JSON' mean when I get an error?

It means the text doesn't conform to the JSON specification — common causes are trailing commas, single quotes instead of double quotes, unquoted object keys, or a missing closing brace/bracket. The error message includes details from the browser's native JSON parser to help you locate the problem.

What's the difference between formatting and minifying?

Formatting (pretty-printing) adds 2-space indentation and line breaks so nested structures are easy to read. Minifying strips all non-essential whitespace to produce the smallest possible single-line string, useful when file size or transmission bandwidth matters.

Does this tool validate JSON Schema, or just JSON syntax?

This tool validates JSON syntax only — that the text is well-formed JSON. It does not check the data against a JSON Schema (i.e., whether specific fields exist or have the right types). Schema validation is a separate concern from syntax validation.

Can I format JSON with comments in it?

No. Standard JSON does not support comments (unlike JSON5 or JSONC). If your input contains // or /* */ comments, JSON.parse will reject it as invalid — remove comments before formatting.

Does formatting change the data, like reordering keys?

No. JSON.stringify preserves the order of object keys as they appear in the parsed result (which follows insertion order per the JSON.parse behavior), and does not alter any values. Only whitespace and indentation are added or removed.

Is my JSON data sent to a server?

No. All parsing, formatting, and minifying happens locally using JavaScript's built-in JSON.parse and JSON.stringify functions running in your browser tab. No network request is made.

Why do trailing commas cause an error?

The JSON specification does not permit a trailing comma after the last item in an object or array (unlike JavaScript object/array literals, which do allow it). A trailing comma is one of the most common reasons hand-written JSON fails to parse.

Can I use single quotes for strings in JSON?

No. JSON requires double quotes for all strings and object keys. Single quotes are valid in JavaScript object literals but not in strict JSON — using them will cause a parse error here.

What's the maximum size of JSON this tool can handle?

There's no hard-coded limit, but extremely large JSON documents (tens of megabytes) may parse slowly since everything runs synchronously on your browser's main thread.

Does the tool support JSON5 or JSONC (JSON with comments)?

No, this tool strictly validates standard JSON per the JSON.parse specification. JSON5 and JSONC are supersets with relaxed syntax (comments, trailing commas, unquoted keys) that are not part of the JSON standard and are not supported here.

JSON Formatter — Beautify, Validate & Minify JSON Instantly

Our JSON Formatter takes raw JSON text and pretty-prints it with 2-space indentation for readability, or minifies it into a single compact line when you need the smallest possible payload. Invalid JSON is caught immediately and shown with a clear error message describing what went wrong, powered by the browser's native JSON.parse. Nothing is uploaded — formatting and validation both happen instantly in your browser as you type.

Your JSON

Formatted output

Your formatted JSON will appear here

How to Use the JSON Formatter & Validator — Free Online Beautifier

1
Paste your raw or minified JSON into the input box.
2
The tool validates and pretty-prints it automatically as you type.
3
Toggle 'Minify' if you need a compact single-line version instead of pretty-printed output.
4
If the JSON is invalid, a clear error message appears explaining the problem. Click 'Copy' once the output looks correct.

Why Use JSON Formatter & Validator — Free Online Beautifier?

JSON (JavaScript Object Notation) is the standard data format for APIs, configuration files, and data interchange between systems. Minified JSON returned by an API — a single unbroken line with no whitespace — is efficient to transmit but nearly impossible for a human to read or debug. Pretty-printing adds consistent indentation and line breaks so nested objects and arrays are visually clear, which is essential when debugging an API response, inspecting a config file, or reviewing a webhook payload. Conversely, when you need to embed JSON in a space-constrained context or minimize payload size, minifying strips all unnecessary whitespace. This tool uses the browser's native, spec-compliant JSON.parse and JSON.stringify — the same engine that powers every JSON operation in JavaScript — so anything it accepts is guaranteed valid JSON, and any error message reflects the exact same parsing rules your application code will hit.

Frequently Asked Questions

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