JSON Validator
Validate JSON syntax instantly. Get clear error messages for invalid JSON.
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Learn more about the JSON Validator
What Does This JSON Validator Do?
This tool checks whether JSON is syntactically valid — correctly matched brackets and braces, double-quoted keys and strings, valid value types, and no trailing commas — and returns a clear valid or invalid status.
Paste any JSON, or drag and drop a .json file, and click Validate. If something's wrong, you get the parser's exact error and location instead of a generic "invalid JSON" message, so common mistakes like a trailing comma, an unquoted key, or a missing bracket are easy to find and fix.
Everything runs locally in your browser; your JSON and files are never sent to a server.
Why Validate JSON?
Catch Errors Early
A single missing comma or unclosed bracket can break an entire application. Validating JSON before using it catches these mistakes before they cause failures downstream.
API Development
When building or testing an API, validating request and response payloads confirms they are well-formed JSON before you spend time debugging application logic.
Config Files
Many tools read JSON configuration files directly. A syntax error in a config file can silently break a build or deployment — validating it first avoids that.
Debugging
When JSON.parse fails somewhere in your code, running the same data through a validator gives you a precise, human-readable error instead of a stack trace.
Example
Here's valid JSON alongside the same object with a trailing comma — a common mistake that causes validation to fail.
{
"user": {
"id": 42,
"name": "Jane Doe",
"email": "jane@example.com",
"active": true,
"roles": ["admin", "editor"]
}
}{
"user": {
"id": 42,
"name": "Jane Doe",
"roles": ["admin", "editor",]
}
}Features
Validate
Check JSON syntax instantly and see a clear valid or invalid status.
Detailed Errors
Invalid JSON shows the exact parser error, so you know precisely what to fix.
Upload a File
Drag and drop or upload a .json file to validate it directly, no copy-pasting required.
Sample Data
Load a sample JSON object to see how validation works before pasting your own.
Reset
Clear the editor and status in one click to start validating a new document.
How to use
Paste your input in the left editor. The output appears automatically on the right. Use the toolbar buttons to copy, download, or transform the result.
- Paste or type your content in the input editor on the left.
- The formatted output is generated automatically.
- Use Copy, Download, or other actions from the output toolbar.
- Click the expand icon to view the output in fullscreen.
FAQ
Is this JSON validator free?
Yes, the JSON validator is completely free to use with no limits, signup, or account required.
Is my JSON data uploaded to a server?
No. Validation runs entirely in your browser using JavaScript, whether you paste JSON or upload a file. Your JSON is never uploaded or sent to a server.
Can I validate a JSON file instead of pasting JSON?
Yes. Drag and drop a .json file onto the input panel, or click the upload icon in the panel header to browse for one. Files up to 5MB are supported.
What does JSON validation check?
It checks that your JSON follows correct syntax — properly closed brackets, quoted keys, valid value types, and no trailing commas.
Can I validate large JSON files?
Yes, the validator handles large JSON documents smoothly since everything runs client-side in the Monaco editor, the same editor used in VS Code.
Does it validate against a JSON Schema?
Currently it validates JSON syntax only. JSON Schema validation is planned for a future update.
What is the difference between JSON validation and formatting?
Validation checks whether your JSON is syntactically correct. Formatting rearranges valid JSON with indentation for readability — it does not check correctness.
Why does my JSON show as invalid when it looks correct?
Common causes are trailing commas, single-quoted strings, unquoted keys, or a missing closing bracket. The error message shows exactly where parsing failed.
Can I fix errors directly in the editor?
Yes, edit the JSON in the input editor and click Validate again to re-check it after making changes.