How to Validate JSON and Find the Error

Validating JSON checks that the text follows the JSON syntax rules, so a parser can read it. A validator can tell you where the first problem is. It cannot tell you whether the data has the fields your application expects, which is a separate schema check.

Last updated: 2 November 2026

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Step-by-step

Paste the JSON into the JSON Validator.
Run the check and read the result. A valid document is confirmed, and an invalid one shows an error message.
Use the position or line information in the message to find the problem in your text.
Fix the first error, then validate again. Later errors are often hidden until the first is fixed.
When the syntax is valid, check the structure against a JSON Schema if your application needs specific fields.

Syntax validity and schema validity

A syntax validator answers one question: can this text be parsed as JSON? A document can be syntactically valid and still wrong for your application, for example a number where you need a string, or a missing field. A JSON Schema validator checks the structure, field types and required properties.

Reading an error message

Parser messages usually name the unexpected character and its position. The real mistake is often just before that point, such as a missing comma at the end of the previous line or an unclosed quote earlier in the text. Look a few characters before the reported position as well as at it.

Common reasons JSON fails validation

These causes account for most failures.

A trailing comma after the last item.
Single quotes, or keys without quotes.
Comments added to a configuration file.
Smart quotes copied from a web page or document.
A truncated response where the closing bracket is missing.

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Frequently asked questions

How do I check if JSON is valid?

Paste it into a JSON validator. If it parses, it is valid JSON. If not, the error message points to the first problem.

Why does the error point to the wrong place?

The parser reports where it noticed the problem, which can be after the mistake. Check the characters just before the reported position.

What is the difference between valid JSON and valid against a schema?

Valid JSON follows the syntax rules. A schema also checks that the data has the right fields and types for your application.

Is an empty string valid JSON?

No. An empty input has no value to parse, so a validator reports an error.