JSON Formatter & Validator
Format, validate, and beautify JSON instantly. Minify JSON for production. Detect and highlight syntax errors. Works offline in your browser.
How to use in 3 steps
No learning curve. No tutorials. Just open and go.
Paste your JSON
Paste raw, minified, or malformed JSON into the input area. Even partial JSON is accepted for validation.
Format or validate
Click Format to prettify with proper indentation, or Validate to check for syntax errors highlighted in red.
Copy the result
Copy the formatted JSON with one click. Use Minify to compress for production use, or Expand to explore nested structures.
Everything you need to know
JSON is the lingua franca of modern web development. Every REST API, every mobile app backend, every webhook payload, and most configuration files use JSON. Developers spend hours every week reading, debugging, and reformatting JSON data.
The SiteConversor JSON formatter does what every developer needs daily: takes minified or malformed JSON and makes it readable in seconds. It also catches the subtle errors that cause runtime exceptions — trailing commas, single-quoted keys, and unbalanced brackets are all flagged immediately with precise error locations.
For teams reviewing API contracts or data schemas: the prettified output with 2-space indentation makes nested structures immediately comprehensible. A 500-character minified JSON payload becomes a clearly structured 30-line document you can understand at a glance.
Security note: like all SiteConversor tools, JSON formatting happens entirely in your browser using JavaScript's built-in JSON.parse and JSON.stringify methods. Sensitive API responses, authentication tokens, and proprietary data schemas never leave your device.
Frequently Asked Questions
What is JSON formatting and why do I need it?expand_more
JSON (JavaScript Object Notation) is the universal data exchange format for APIs and web services. Minified JSON (all on one line, no spaces) is efficient for transmission but impossible to read. A JSON formatter adds line breaks and indentation (pretty-printing) to make the structure human-readable for debugging and review.
What is JSON validation?expand_more
JSON has strict syntax rules: keys must be in double quotes, values must be valid types, commas and brackets must be balanced. A JSON validator checks these rules and tells you exactly which line and character contains an error. This is essential when debugging API responses or configuration files.
What is the difference between JSON and JavaScript objects?expand_more
JSON is a strict subset of JavaScript object literal syntax. Key differences: JSON requires double-quoted keys (not single quotes, no unquoted keys), does not allow trailing commas, does not support undefined or function values, and does not allow comments. Many 'JSON errors' are caused by copying JavaScript objects that have these JavaScript-only features.
Can I use this to format JSON from API responses?expand_more
Yes. Open your browser's developer tools, find the API response in the Network tab, copy the response body, and paste it here. The formatter will instantly pretty-print it for review.
Does this tool support JSON5 or JSONC (JSON with comments)?expand_more
The tool validates strict RFC 8259 JSON. JSON5 (with comments and unquoted keys) and JSONC are not supported. However, it will identify exactly where the non-standard syntax is so you can fix it.
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