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JSON Validator & Formatter: Validate and Format JSON Online

Validate, format, and minify JSON with clear error guidance in a free online tool.

This tool quickly checks JSON syntax against the official standard to confirm it is correct or highlight any errors. It reformats messy or minified JSON into a readable, indented layout to make understanding and debugging easier. You can also minify JSON, removing all extra whitespace for more efficient storage or transmission. Alongside these core functions, the validator provides detailed feedback about common syntax mistakes, such as incorrect quoting, trailing commas, and unescaped characters. The interface shows summary stats including the root data type, nesting depth, total keys, and size reductions from minification. Whether you're troubleshooting API payloads or tidying config files, this tool pinpoints exactly where fixes are needed and offers hints for how to correct them.

Features

  • Syntax validation with detailed error messages
  • Pretty-print JSON for improved readability
  • Minify JSON by removing unnecessary whitespace
  • Complete structure analysis

Use cases

  • Debugging API payloads with invalid JSON
  • Formatting nested JSON for easier review
  • Minimizing JSON size for production use
  • Reformats minified or messy JSON into a clean, indented structure

Frequently asked questions

What is the difference between JSON and JavaScript object literals?

JSON requires all keys and strings to be double-quoted, forbids single quotes, trailing commas, comments, and expressions, unlike JavaScript object literals which allow these.

Why does my JSON look valid but still fail to parse?

Invisible characters like byte order marks, zero-width spaces, or incompatible line endings can cause parsing errors even if the JSON looks correct.

Can JSON handle large numbers?

JSON has no size limit, but JavaScript parsing uses double-precision floats which can lose precision with very large integers; such numbers should be encoded as strings.

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