MasterTool

JSON Formatter and Validator

Use json formatter and validator locally, without uploading your data.

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What this tool does

Use json formatter and validator locally, without uploading your data. Strict JSON, not JavaScript objects or comments; duplicate keys follow JavaScript parsing semantics and large integers may lose precision.

How to use the JSON Formatter and Validator

  1. Enter or select json input.
  2. Enter or select indentation.
  3. Read the calculated result; change any measurement to compare alternatives.

Formula

parse JSON with JSON.parse then serialize with JSON.stringify and selected indentation
value
JSON input
indent
Indentation

Strict JSON, not JavaScript objects or comments; duplicate keys follow JavaScript parsing semantics and large integers may lose precision.

Worked example

For json formatter and validator, the following measurements illustrate the exact method: JSON input: {"name":"MasterTool","free":true}; Indentation: 2.

Inputs

  • JSON input{"name":"MasterTool","free":true}
  • Indentation2 spaces

Result

  • Valid formatted JSON{ "name": "MasterTool", "free": true }

Results explained

Valid formatted JSON
Valid formatted JSON from the formula above. Strict JSON, not JavaScript objects or comments; duplicate keys follow JavaScript parsing semantics and large integers may lose precision.

Frequently asked questions

parse JSON with JSON.parse then serialize with JSON.stringify and selected indentation

Strict JSON, not JavaScript objects or comments; duplicate keys follow JavaScript parsing semantics and large integers may lose precision.

No. Content stays in your browser and no API is called.

Copy the result, review it in your project, and test it in the intended environment.

No. Syntax checks and conversions cannot replace application-specific testing, security review or accessibility review.