Modern Online JSON Formatter, Validator & Beautifier
JSONGuy is a modern JSON formatter that pretty-prints and validates JSON in your browser — with syntax highlighting and a collapsible tree view. Supports JavaScript-style JSON and Python objects (comments, single quotes, unquoted keys, trailing commas, None/True/False). 100% client-side, no sign-up required.
Click Beautify to format your JSON.
JSON Beautifier
Pretty-print raw or compact JSON with 2 or 4 space indentation, GitHub-style syntax highlighting, and a collapsible tree view for easy navigation.
JSON Validator
Live validation catches syntax errors instantly and reports the exact line and column, so you can fix broken JSON in seconds.
JavaScript & Python Object Syntax
Paste modern JavaScript-style JSON or a Python dict — unquoted keys, single quotes, trailing commas, comments, and None/True/False — and normalize it into strict, standards-compliant JSON.
Frequently Asked Questions
What is a JSON formatter?
A JSON formatter takes raw or compact JSON and reformats it with indentation and line breaks so it is easy to read. JSONGuy also validates the structure and highlights syntax errors with their exact line and column.
How do I format JSON online?
Paste your JSON into the input box and click the Beautify button between the two panes. JSONGuy pretty-prints the JSON in the output pane, and you can use the tree view to navigate nested objects and arrays.
Can I format JavaScript-style JSON or Python objects?
Yes. JSONGuy supports relaxed JavaScript object syntax (JSON5) — unquoted keys, single-quoted strings, trailing commas, and line or block comments — and Python dicts with None, True, and False. It normalizes all of them into standard JSON.
How do I validate JSON?
Click Validate, or rely on the live status bar at the bottom of the tool. Invalid input is reported immediately with the error message and the offending line and column.
Is my JSON data sent to a server?
No. All formatting and validation runs locally in your browser. Your JSON is never uploaded or stored on a server.
What makes JSONGuy a modern JSON formatter?
Unlike legacy formatters, JSONGuy is built for modern development. It understands relaxed JavaScript-style JSON and Python objects (unquoted keys, single quotes, trailing commas, comments, None/True/False), offers GitHub-style syntax highlighting, a collapsible tree view, live validation, and runs entirely in your browser with no server round-trips.