JSON Validate Lint
Validate and lint your JSON syntax in real-time. Detect bracket, quote, comma errors with precise line and column positioning.
About JSON Validate Lint
Our free online JSON Validate Lint tool is a powerful syntax validator that checks your JSON data for errors in real-time. Powered by the JSONLint engine, this tool performs deep parsing of your JSON input and detects common syntax issues including mismatched brackets, unquoted keys, trailing commas, invalid escape sequences, and unclosed strings.
When an error is found, the validator provides detailed diagnostic information including the exact line number, column position, and error type. This precise error reporting makes it easy to locate and fix issues quickly, even in large and complex JSON files. The error context display shows the problematic line of code highlighted for instant identification.
The tool also includes formatting capabilities. If your JSON is valid, you can format it with proper indentation or minify it for production use. The auto-validate mode continuously checks your JSON as you type, providing instant feedback on syntax errors.
All processing happens directly in your browser, so your JSON data never leaves your device. This ensures complete privacy and security for your sensitive data, including API keys, tokens, and confidential information.
Related JSON Tools
Features
Real-Time Validation
Automatically validates your JSON as you type with instant error detection and feedback.
Precise Error Location
Reports exact line number, column position, and character offset for every syntax error found.
Error Context Display
Shows the problematic line highlighted so you can instantly see what went wrong.
Bracket & Quote Detection
Detects mismatched brackets, unclosed quotes, and missing commas automatically.
Format & Minify
Format valid JSON with indentation or minify it for production use with one click.
Copy & Download
Copy formatted JSON to clipboard or download as a .json file for local use.
Syntax Highlighting
CodeMirror editor with JSON syntax highlighting, line numbers, bracket matching, and search.
Structure Statistics
View counts of objects, arrays, nesting depth, and overall structure complexity.
Privacy First
All validation happens in your browser. Your data never leaves your device.
How to Use
Paste Your JSON
Copy and paste your JSON into the editor. You can also click "Sample JSON" for valid data or "Load Invalid JSON" to see error detection in action.
View Validation Results
If auto-validate is enabled, results appear instantly. Otherwise, click Validate. Green means valid JSON, red shows errors with details.
Fix Errors
If errors are found, check the error details including line number, column, and error context. Fix the issue and validation will update automatically.
Format or Export
Once valid, use Format to beautify or Minify to compress. Copy to clipboard or download as a .json file.
Frequently Asked Questions
What does JSON validation check for?
JSON validation checks for syntax errors that violate the JSON specification. Common errors include: mismatched or unclosed brackets/braces, unquoted object keys, single quotes instead of double quotes, trailing commas before closing brackets, invalid escape sequences in strings, missing commas between values, control characters in strings, and malformed numbers or boolean values.
What is JSONLint?
JSONLint is a popular open-source JSON validation library originally created by Zachary Carter. It provides a JavaScript parser that can validate JSON strings and provide detailed error messages including line number, column position, and the type of syntax error. This tool uses JSONLint's parsing engine to provide accurate and detailed validation results.
How do I fix a "Unexpected token" error?
An "Unexpected token" error means the parser encountered a character it didn't expect at that position. Common causes include: a trailing comma before a closing bracket (e.g., `｛"a": 1,｝`), a single quote instead of double quote (`｛'key': 'value'｝`), a missing comma between key-value pairs, or an unquoted key name. Check the line and column position provided in the error details to locate the issue.
Does it support JSON with comments?
Standard JSON does not support comments. If you need to validate JSON with comments (like configuration files), you'll need to remove the comments first. The validator strictly follows the JSON specification (RFC 8259), which does not include comment syntax. Some tools use JSONC (JSON with Comments) or JSON5, but those require different parsers.
Is this JSON validation tool free?
Yes, it is completely free to use with no registration, sign-up, or limits. You can use it as many times as you need for personal, educational, or commercial projects without any restrictions.
Does it work offline?
Yes, once the page is loaded, all JSON validation happens entirely in your browser using JavaScript. No server communication is needed, so you can use it even without an internet connection after the initial page load.
Can it validate large JSON files?
Yes, this tool can handle large JSON files efficiently. Since all processing is done client-side, the performance depends on your device's capabilities. For very large files (several megabytes), validation may take a few extra moments, but the results are just as accurate.
What is the difference between validation and linting?
In the context of JSON, validation and linting are often used interchangeably. Strictly speaking, validation checks whether the JSON conforms to the specification (is it valid JSON?), while linting may also check for style and best practices (is it well-formatted JSON?). This tool primarily validates syntax but also provides formatting options to help you produce clean, well-structured JSON.
Is my JSON data secure?
Absolutely. All JSON validation happens directly in your browser using JavaScript. Your data is never sent to any server, stored, or logged. This ensures complete privacy and security for sensitive information like API responses, tokens, and configuration data.