Validate, format, and minify JSON with configurable indentation.
Formatted Output
Paste any JSON and choose your preferred indentation. Minify removes all whitespace for compact output. Invalid JSON shows an error message.
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What is the JSON Formatter?
JSON (JavaScript Object Notation) is a lightweight data format used everywhere: APIs, config files, databases, and web apps. A JSON formatter reads any valid JSON string and reformats it with consistent indentation, line breaks, and syntax highlighting, making it human-readable. It also detects errors like missing commas or mismatched braces, helping you catch bugs before they break your app.
How it works
The formatter parses your JSON string character by character, validates its structure against JSON rules, and reconstructs it with proper indentation (typically 2 or 4 spaces per level). It organises objects and arrays into nested blocks, aligns colons and commas, and flags syntax errors with line numbers. You can toggle between beautified (readable) and minified (compact, no whitespace) modes depending on whether you're developing or shipping code.
Nested objects and arrays are indented by depth, showing structure clearly at a glance.
{"error":"timeout"}
{
"error": "timeout"
}
Even single-line JSON is reformatted for consistency and easier editing.
How to use the JSON Formatter
Copy or paste your JSON code into the input field—it can be minified, malformed, or from an API response.
Click 'Format' (or the tool auto-formats as you type).
Review the output: each level is indented, syntax is validated, and errors are highlighted with line numbers.
If errors appear, check the message; common issues are missing commas, trailing commas in arrays, or unclosed braces.
Switch between 'Beautify' and 'Minify' modes as needed—use beautified for development, minified for production.
Copy the formatted JSON and paste it into your editor, config file, or API documentation.
Benefits
Spot syntax errors instantly—malformed JSON is flagged with line numbers and descriptions, saving hours of debugging.
Improve code readability—indented, properly spaced JSON is easier for you and your team to understand and maintain.
Speed up API debugging—paste raw API responses directly and see their structure clearly instead of squinting at a single line.
Save file size—minify your JSON for production to reduce bandwidth and server load by removing all unnecessary whitespace.
Validate before deploying—catch errors in config files, credentials, or data before they break your application.
Work faster—no installation, login, or IDE plugins needed; format JSON instantly in your browser, anywhere.
Tips & common mistakes
Common mistakes
Forgetting commas between key-value pairs or array items—the formatter will catch this, but avoiding it saves rework.
Using single quotes instead of double quotes (JSON requires double quotes, not apostrophes or single quotes).
Leaving trailing commas after the last item in an array or object (valid in JavaScript, invalid in JSON).
Mixing tabs and spaces for indentation—stick to one style (usually 2 or 4 spaces) for consistency and to avoid parser errors.
Tips
If your JSON spans multiple lines and the formatter flags unexpected errors, check for invisible characters (non-breaking spaces, line feeds) that break the parser.
Use minified JSON in production to cut file sizes by 10–30%, but always keep beautified versions in your codebase for maintenance.
Paste API responses directly—the formatter handles incomplete or malformed JSON and tells you exactly what's wrong.
Integrate this formatter into your workflow: bookmark it, use it as a quick reference, or export formatted JSON to your clipboard with one click.
Frequently asked questions
What's the difference between beautified and minified JSON?
Beautified JSON is human-readable with indentation and line breaks; minified JSON removes all whitespace to reduce file size. Use beautified for development and testing, minified for production and APIs to save bandwidth.
Can the formatter fix broken JSON for me?
The formatter detects and reports errors but cannot always fix them automatically—for example, it can't guess whether you meant a missing comma or a wrong value. Use the error message as a guide to find and fix the syntax mistake manually.
Is my data safe if I paste it into the online formatter?
FreeTooz formatters process your data in your browser (client-side), so it never leaves your device or hits our servers. Your passwords, API keys, and credentials are never logged or stored.
Can I format very large JSON files?
Yes, the formatter handles large files, but extremely large files (>10 MB) may slow down your browser. For massive files, consider using a command-line tool like `jq` or saving to a file and processing locally.
What if my JSON includes non-English characters or emojis?
JSON formatters handle Unicode and emojis correctly as long as they're properly escaped or encoded. The formatter preserves them and reformats the structure without altering the content.
Why does the formatter reject my JSON even though it looks correct?
Common culprits: single quotes instead of double quotes, trailing commas, unescaped newlines in strings, or mismatched braces. The error message points to the line—check that line and the one before it carefully.