JSON Validator
JSON Validator
Validate JSON and pretty-print it.
Runs entirely in your browser
How to use this tool
- Fill in the inputs.
- Read the result.
- Copy or download as needed.
About the JSON Validator
The JSON Validator checks whether a block of JSON text is syntactically correct according to the strict JSON specification, and if it is valid, displays a clean, pretty-printed version of it alongside a clear success message. If the JSON is invalid, it shows a specific error message describing what went wrong.
While this shares some functionality with the JSON Formatter, this tool is focused specifically on the validate-and-confirm workflow: a single button that tells you definitively whether your JSON is correct, which is useful when correctness is your only concern rather than reformatting an existing structure.
When you click the validate button, the tool attempts to parse your input using the browser's native, spec-compliant JSON parser. If parsing succeeds, it confirms the JSON is valid and displays a nicely indented version of the parsed data as a bonus, so you can visually inspect its structure. If parsing fails, the browser's parser returns a specific error message, typically identifying the type of problem and often the approximate location in the text where it occurred, which the tool displays directly so you can jump straight to fixing the actual issue.
Because this uses the same strict, standards-compliant parsing engine as the rest of the JSON tools on this site, a "valid" result here means the JSON will also be accepted by virtually any other standard JSON parser, including those used by APIs, databases, and programming languages.
Common use cases
- Quickly checking whether a JSON snippet from documentation, a support ticket, or a colleague is syntactically correct.
- Validating a configuration file's JSON before deploying it to a production system.
- Catching JSON syntax errors during development before they cause a runtime error in an application.
- Verifying that JSON generated by a script or another tool is well-formed.
- Teaching or learning proper JSON syntax by testing different inputs and observing the resulting error messages.
Tips and best practices
- If validation fails, read the specific error message carefully — it usually names the exact type of syntax problem and often an approximate position in the text.
- Common invalid JSON patterns include trailing commas, single-quoted strings, unquoted keys, and using `undefined` instead of `null` — all of which are valid in JavaScript but not in strict JSON.
- A successful validation also gives you a neatly formatted version of your JSON as a bonus, which can save you a separate trip to the JSON Formatter tool.
- For a workflow that always needs the reformatted output (rather than just a validation check), the JSON Formatter tool's dedicated Format and Minify buttons may fit better.
