How can I check if JSON is valid?
Paste JSON or load a file and click “Validate JSON” – or use automatic validation while typing.
JSON Validator
Validate JSON for free, locate syntax errors and analyse structure – no sign-up, with file upload, clear error display and local processing in your browser.
Your JSON data is validated directly in your browser. It is neither transmitted nor stored.
Your JSON data is validated locally in your browser only and is not stored.
Drop a JSON file here or select one (.json, .txt)
Understanding and using the JSON Validator
What is a JSON Validator?
A JSON validator checks whether text conforms to JSON syntax rules. It shows whether JSON is valid and where syntax errors occur.
What does valid JSON mean?
Valid JSON consists of correctly structured objects, arrays, strings, numbers, booleans or null values.
Must JSON start with an object?
No. Arrays and primitive values such as strings, numbers, true, false or null are also valid root values.
Why is my JSON invalid?
Common causes include missing or trailing commas, missing quotes, single quotes, unquoted keys, unclosed brackets, comments or invalid escape sequences.
Are comments allowed in JSON?
No. Standard JSON does not allow comments such as // or /* */.
Are trailing commas allowed?
No. There must be no comma after the last element in an object or array.
Why must keys use double quotes?
The JSON standard requires double quotes for object keys and string values.
What is the difference between JSON and a JavaScript object?
JavaScript object literals allow more syntax than JSON, such as unquoted keys, comments or trailing commas.
What is the difference between JSON Validator and JSON Formatter?
The validator checks validity and shows errors. The formatter presents valid JSON in a readable form and usually assumes valid syntax.
Is JSON data stored?
No. Validation happens entirely locally in your browser.
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Frequently asked questions about the JSON Validator
What does a JSON validator do?
It checks whether text is syntactically valid JSON and shows position and cause when errors occur.
Why is my JSON invalid?
Common causes include missing commas, trailing commas, wrong quotes, unquoted keys or unclosed brackets.
Must JSON always start with a curly brace?
No. Arrays and primitive values are also valid JSON.
Can an array be valid JSON?
Yes. An array on its own is fully valid JSON.
Is a single number valid JSON?
Yes. Example: 42 is valid JSON.
Is null valid JSON?
Yes. null is a valid JSON value.
Are single quotes allowed?
No. JSON requires double quotes.
Must object keys be quoted?
Yes. Object keys must be enclosed in double quotes.
Are comments allowed in JSON?
No. Comments are not part of the JSON standard.
Are trailing commas allowed?
No. There must be no comma after the last element.
What does an unexpected character mean?
The parser expected different syntax at that point, such as a comma, bracket or quote.
How do I find the faulty line?
The tool shows line, column and a text excerpt with the error position marked where possible.
Why can the exact error position differ between browsers?
Different browsers format parser messages differently. The tool evaluates multiple formats.
Can the tool automatically repair invalid JSON?
No. It provides hints but does not automatically repair JSON.
Can I validate a JSON file?
Yes. .json and .txt files can be loaded locally.
Can I validate large JSON files?
Yes, up to 10 MB. Larger files are rejected.
Is my JSON data stored?
No. Everything happens locally in your browser.
Are HTML or script contents executed?
No. JSON is only parsed and displayed as text – never executed.
What is the difference between JSON and JSON5?
JSON5 allows comments, single quotes and trailing commas. This tool supports standard JSON only.
What is the difference between JSON Validator and JSON Formatter?
The validator checks validity and errors. The formatter formats and minifies valid JSON.
Can I copy the validation result?
Yes. For valid or invalid JSON, a compact summary can be copied.