What JSON errors does it detect?

Missing commas, unclosed brackets, trailing commas, invalid escape sequences, duplicate keys, and more.

Does it support JSON5 or JSONC?

This tool validates strict JSON (RFC 8259). Comments and trailing commas will be flagged as errors.

Yes — drag and drop a .json file onto the editor or use the file upload button.

No. Validation happens entirely in your browser. Your data never leaves your device.

Validate JSON syntax and find errors instantly. Works in your browser. Free, no signup.

No sign-up Batch convert 100% free

How useful is JSON Validator?

Paste your JSON into the input area

The validator checks syntax in real time as you type

View error details with line numbers if validation fails

Fix errors and re-validate until you see the green checkmark

Format and beautify JSON data with syntax highlighting.

Create beautiful CSS gradients visually and copy the code.

Pick colors from any format and convert between HEX, RGB, HSL.

Test and debug regular expressions with real-time matching.

Generate placeholder text for designs and mockups.

Format and indent HTML code for better readability.