JSON Formatter & Validator
Paste messy JSON on the left, get clean formatted JSON on the right. Free, instant, no signup.
Formatted JSON will appear here...
How to Format JSON Online
JSON (JavaScript Object Notation) is the universal data format for APIs, config files, and web applications. When you receive minified or messy JSON, this tool makes it readable instantly.
Features
- Instant Formatting — Paste JSON and see it formatted as you type. Adjustable indentation (1-8 spaces).
- Syntax Validation — Invalid JSON is flagged with an error message showing the exact line and position of the problem.
- Copy & Download — One-click copy to clipboard or download as .json file.
- Minify Mode — Compress formatted JSON back to a single line to reduce file size.
- Privacy First — All processing happens in your browser. No data is ever sent to a server.
Why Format JSON?
Minified JSON is efficient for machines but impossible for humans to read. Formatting adds indentation and line breaks, making nested structures visible at a glance. This is essential for debugging API responses, inspecting configuration files, and understanding data structures.
Frequently Asked Questions
Is this tool free?
Yes. Completely free, no limits, no registration required.
Is my JSON data secure?
Absolutely. Everything runs locally in your browser. We never see, store, or transmit your data.
What happens if my JSON is invalid?
An error message will appear with the exact location of the syntax error, helping you fix it quickly.
Can I format very large JSON files?
Browser performance varies, but files up to 5-10MB typically work fine. For very large files, consider using a command-line tool like jq.