What is JSON validation?

JSON validation checks whether a string conforms to the JSON specification (RFC 8259). A valid JSON document must use double-quoted strings, have no trailing commas, no comments, and all brackets and braces must be properly matched. A JSON validator parses the input and reports any syntax errors with their exact location.

What are the most common JSON syntax errors?

The most common JSON errors are: trailing commas after the last item in an array or object, using single quotes instead of double quotes, unquoted property keys, including JavaScript-style comments (// or /* */), and missing commas between elements. This validator detects all of these and can auto-fix them.

Is my JSON data safe when using this validator?

Yes, completely. This JSON validator runs 100% in your browser using JavaScript. Your data never leaves your computer and nothing is sent to any server. You can even use it offline once the page has loaded.

JSON Validator

Paste or drop your JSON to validate it instantly. Get precise error messages with line numbers, auto-fix common issues, and see detailed structure stats. Everything runs in your browser — your data stays private.

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Input JSON

Drop JSON file here

Pretty-Printed Output

Validated JSON will appear here...

? Paste JSON to validate

Enter or upload JSON data to check its validity.

Auto-Fix Suggestions

JSON Statistics

Data Types

About JSON Validation

JSON (JavaScript Object Notation) is a strict data format. Unlike JavaScript objects, JSON requires double-quoted strings, no trailing commas, no comments, and no undefined values. A single misplaced character will make your entire document invalid.

This validator checks your JSON against the RFC 8259 specification and provides precise, actionable error messages. When it finds common mistakes (trailing commas, single quotes, comments), it offers one-click fixes so you can correct your JSON without manual editing.

Features

Detailed error messages with exact line and column numbers
Error line highlighting in the input area
Auto-fix: trailing commas, single quotes, unquoted keys, comments
JSON structure statistics: key count, depth, size, data types
Pretty-print validated JSON with proper indentation
Drag-and-drop file upload for .json files
100% client-side — your data never leaves your browser

JSON Validator

About JSON Validation

Features

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Frequently Asked Questions