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Edwin Lab

JSON Validator & Formatter

Check an API response, find a syntax error, or make a JSON payload easier to read. Your text stays in this browser.

Strict JSON only. Input limit: 5 MiB UTF-8. Your content is not uploaded.

Validation checks JSON syntax. It does not check an API schema or application-specific rules.

Ready. Choose an action to check your JSON.

How to validate or format JSON

  1. Paste a JSON value or load an example.
  2. Choose an indentation size, then select Validate JSON, Format, or Minify.
  3. Copy or download a formatted result when you need to keep it.

JSON is a text format with quoted property names and double-quoted strings. This validator checks syntax, not whether fields match an API schema or application rules.

Common JSON syntax errors

Trailing comma

Invalid: {"name":"Edwin",}. Remove the comma after the last property.

Single quotes

Invalid: {'name':'Edwin'}. Use double quotes: {"name":"Edwin"}.

Missing comma

Invalid: {"name":"Edwin" "active":true}. Add a comma between the properties.

Comments

JSON does not allow JavaScript comments such as // note or /* note */. Remove them before parsing strict JSON.

Example JSON

This sample is valid JSON. Formatting changes whitespace and indentation while retaining source value tokens, key order, duplicate properties, escapes, and large number text.

{
  "service": "profile-api",
  "enabled": true,
  "retryLimit": 3,
  "regions": ["Jakarta", "Singapore"]
}

Frequently asked questions

Why is my JSON invalid?

Check for missing commas or colons, unquoted property names, single quotes, trailing commas, comments, and unmatched brackets. The tool reports the first syntax error with its line and column.

Are comments allowed in JSON?

No. This page validates standard JSON and rejects line and block comments, along with trailing commas.

Will formatting change large numbers?

Formatting and minifying copy the original JSON value tokens instead of converting numbers to JavaScript values. Their text, including large number tokens and negative zero, is retained.

Is my JSON uploaded?

No. Validation and formatting run locally in your browser. This page does not send your input to an API or put it in the URL.

A syntactically valid JSON document can still fail a service's schema or business rules. Consumers may also handle duplicate object keys differently.

Related developer tools

Compare payload structure with JSON Diff, convert configuration with the JSON ↔ YAML Converter, or turn records into a table with the JSON ↔ CSV Converter. Browse all Developer Tools.