JSON Validator
Validate a JSON snippet in your browser. The checker reports syntax errors such as missing commas, unquoted property names, or trailing commas.
Check JSON syntax before using an API payload, configuration file, or data export. JSON requires double-quoted strings and property names, and does not allow comments or trailing commas.
Checks JSON syntax only, not an API contract or application schema. Input stays in this browser.
🔒 All processing happens in your browser — files never leave your device. Your input stays in this browser and is not uploaded to Smart Online Tools.
How it works
- Paste JSON into the editor.
- Select Validate JSON.
- Fix any reported syntax error and validate again.
Good to know: Syntax validation does not check a JSON Schema or whether an API accepts the data.
Privacy and processing
All processing happens in your browser — files never leave your device. Your input stays in this browser and is not uploaded to Smart Online Tools.
What JSON validation checks
JSON is a text format with strict rules: strings and property names use double quotes, values use JSON types, and comments and trailing commas are not allowed. This page uses the browser's JSON parser to check those rules.
A successful parse only means the text is valid JSON. It does not prove that required fields are present or that a service will accept the values. For those checks, compare the data with the API documentation or its JSON Schema.
Frequently asked questions
Does JSON support comments?
Standard JSON does not. Remove comments before validating it.
Can a formatter repair invalid JSON automatically?
It can only format valid input. Fix syntax errors first, then format.
Is JSON the same as JavaScript object syntax?
No. JSON is stricter: keys and strings require double quotes, and executable expressions are not allowed.
What does JSON Validator do?
Check JSON syntax and see parser errors before using a payload or config file. Validate a JSON snippet in your browser. The checker reports syntax errors such as missing commas, unquoted property names, or trailing commas.
Does this tool upload my files or input?
Your input stays in this browser and is not uploaded to Smart Online Tools.