JSON Formatter & Validator

About the JSON Formatter

Paste minified or messy JSON and turn it into readable, indented output, or squeeze it back into a single line. The formatter also validates your JSON and points out syntax errors such as a missing comma or an unquoted key. It runs entirely in your browser, so API responses, tokens and config files stay private.

How to use the JSON Formatter

1. Paste your JSON into the input box.
2. Click Format to beautify it with indentation, or Minify to remove whitespace.
3. If the JSON is invalid, read the error message to find the problem.
4. Copy the result or download it.

Common JSON errors and how to fix them

• Trailing comma: {"a": 1,} is invalid. Remove the comma after the last item.
• Single quotes: JSON needs double quotes, so use "name" rather than 'name'.
• Unquoted keys: {name: 1} is valid JavaScript but not valid JSON.
• Comments: standard JSON does not allow // or /* */ comments.
• Special values: undefined, NaN and functions are not allowed. Use null instead.

Format or minify?

Format (also called beautify or pretty-print) adds line breaks and indentation so people can read nested objects and arrays. Minify removes all unnecessary whitespace, making the file smaller for sending over a network or storing in a config value. The data is identical either way.

FAQ

How do I check if my JSON is valid?

Paste it into the formatter. Valid JSON is formatted straight away; invalid JSON shows an error describing what went wrong.

Is it safe to paste API keys or private data?

The formatter runs locally in your browser and does not send your JSON anywhere. As a habit, still avoid pasting live secrets into any website.

What does minify JSON mean?

Minifying removes spaces, tabs and line breaks that are not needed, so the same data takes up less space.

Can it handle large JSON files?

Yes, within the limits of your browser's memory. Files of several megabytes usually format in under a second.

Why does JSON not allow trailing commas?

The JSON specification is deliberately strict so every parser reads the same data the same way. A comma after the last item is not part of that grammar.