JSON Validator
Validate JSON syntax instantly. Get clear error messages for invalid JSON.
What is JSON Validation?
JSON validation is the process of checking whether a piece of text follows the JSON specification — correctly matched brackets and braces, double-quoted keys and strings, valid value types, and no trailing commas. Valid JSON can be parsed reliably by any language or library; invalid JSON causes a parser to throw an error, often stopping an application in its tracks.
Unlike a JSON formatter, which only changes whitespace, a JSON validator checks correctness. It doesn't change your data at all — it simply tells you whether the JSON is syntactically valid and, if not, exactly where the parser failed and why. This makes it the first thing to reach for whenever JSON is coming from an untrusted or unfamiliar source: a hand-edited config file, an API response, or JSON pasted from a chat or document.
Common syntax errors include trailing commas after the last item in an object or array, single-quoted strings instead of double-quoted, unquoted object keys, and missing or extra brackets. These are easy to miss by eye in a large document but are caught instantly by a validator.
This page lets you validate JSON online for free, directly in your browser. Paste any JSON and click Validate to get an immediate valid or invalid result, with a precise error message when something is wrong — nothing is uploaded or 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.
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.