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Format and validate JSON

Make JSON readable, compact it, or find exactly where it is invalid.

Processed in your browser. Your files stay on this device. Nothing is uploaded to our servers.

Indentation

Your JSON is processed only in your browser and never sent or logged.

How to use JSON Formatter & Validator

  1. 1

    Paste JSON or open a .json file.

  2. 2

    Select Format (2 or 4 spaces) or Minify.

  3. 3

    Review errors or the highlighted result, then copy or download it.

About JSON Formatter & Validator

The validator follows the JSON standard (RFC 8259) strictly and reports the exact line and column of problems such as trailing commas, single quotes, missing commas or invalid escapes. Formatting keeps every value exactly as written: large numbers like 12345678901234567890 and decimals like 1.10 are not rounded or rewritten, which ordinary JavaScript-based formatters often do. Duplicate keys are flagged. Explore the structure in the tree view and download the result. Your JSON is processed only in your browser and is never sent or logged.

Frequently asked questions

Why does it reject comments or trailing commas?

They are not allowed in standard JSON. Remove them, or use a JSON5 tool if your project uses that format.

Will formatting change my numbers?

No. Numbers and strings are kept exactly as written.

Is my JSON sent anywhere?

No. It is processed only in your browser.