Free JSON Formatter & Validator

JSON formatting (also called prettifying or beautifying) adds consistent indentation and line breaks to compact JSON data so it becomes human-readable. Formatted JSON is much easier to scan, debug, and edit by hand. This tool lets you choose 2 spaces, 4 spaces, or tabs for indentation and applies syntax highlighting so keys, strings, numbers, booleans, and nulls are instantly distinguishable.

The validator parses your input using the browser's native JSON parser. If the JSON is malformed, you get a detailed error message showing the approximate line number and character position of the problem, along with a description of what the parser expected. Common issues include trailing commas, unquoted keys, single quotes instead of double quotes, and missing closing brackets.

Prettifying adds whitespace (spaces, tabs, newlines) to make JSON readable. Minifying strips all unnecessary whitespace to produce the most compact representation. Minified JSON is ideal for API payloads, configuration files transmitted over the network, and storage where size matters. Both operations preserve the data exactly — only formatting changes.

The most frequent errors are trailing commas after the last item in an array or object, single quotes instead of double quotes around keys and strings, unquoted property names, and missing or extra brackets. Paste your JSON into this tool and click Validate — the error message will point you to the exact location so you can fix it quickly.

Yes. The formatter processes JSON entirely in your browser, so there is no upload or server-side limit. Files up to several megabytes are handled smoothly on modern devices. For very large files the tree view may be slower to render, but formatting and validation remain fast.

Absolutely. All parsing, formatting, and validation happen in your browser using JavaScript. Your JSON is never sent to any server. This makes the tool safe for API keys, configuration files, and any other sensitive data.

The tree view displays your JSON as a collapsible hierarchy. Click any object or array node to expand or collapse it. This is especially useful for exploring deeply nested structures or large API responses where you need to locate a specific field without scrolling through hundreds of lines.