JSON Formatter
Format, minify, and validate JSON with syntax highlighting — entirely in your browser.
Paste JSON to get started.
Format & Validate JSON Instantly — No Upload Required
Zolkit's JSON Formatter runs entirely in your browser. Paste any JSON string and get instant syntax-highlighted output with key counts and nesting depth — zero data sent to any server.
100% Private
All parsing and formatting happens locally in your browser using the native JSON API. Your data never leaves your device.
Instant Formatting
Results appear as you type. No button press needed — the output updates in real time as you paste or edit your JSON.
Syntax Highlighting
Keys, strings, numbers, booleans, and nulls are each colored differently for maximum readability at a glance.
Format or Minify
Choose 2-space or 4-space indentation for readable output, or switch to Minify mode to produce compact single-line JSON.
Validation & Stats
See whether your JSON is valid, how many total keys it contains, and the maximum nesting depth — all instantly updated.
Completely Free
No account, no sign-up, no ads. Zolkit JSON Formatter is free to use forever with no rate limits.
How to Format JSON
- 1
Paste your JSON string into the left panel. The formatter detects it immediately.
- 2
Choose Format (with 2 or 4-space indent) or Minify from the settings bar.
- 3
Copy the syntax-highlighted result or download it as a .json file.
Frequently Asked Questions
Is my JSON data sent to a server?
No. All processing uses the browser's built-in JSON.parse and JSON.stringify APIs. Your data never leaves your device, making this safe for sensitive config files, API responses, and credentials.
What's the difference between Format and Minify?
Format produces human-readable JSON with configurable indentation (2 or 4 spaces) and line breaks. Minify strips all unnecessary whitespace to produce the smallest possible JSON string — ideal for network payloads.
What does Validate mode do?
Validate mode parses your JSON and immediately reports whether it is structurally valid. If invalid, it shows a description of the parse error to help you locate the problem.
What does 'max depth' mean?
Max depth is the deepest level of nesting in your JSON object or array. For example, {"a": {"b": {"c": 1}}} has a depth of 3. High depth values can indicate overly complex data structures.
Can I format large JSON files?
Yes. Since processing is in-browser, performance is limited only by your device's memory and CPU. Multi-megabyte JSON files are handled without any size restrictions from our side.
Does it support JSON5 or JSONC (comments)?
Currently only strict JSON (RFC 8259) is supported. JSON5 and JSONC with comments will cause a parse error. Strip comments before pasting, or use the error message to locate unsupported syntax.