JSON Validator
Paste JSON to check whether it is valid; if not, the error position, context and likely cause are shown.
- Runs in your browser
- Free to use
About this tool
A single stray comma turns a configuration file into an error message with no line number. The JSON Validator parses your document in the browser and answers plainly: valid, with the root type, value count and nesting depth, or invalid, with the line and column, a snippet of context and hints about the most common mistakes.
Fix it, then tidy it with the JSON Formatter or shrink it with JSON Minify.
How to use it — quick steps
- 01
Enter the json
Type or paste the json in the field above. Nothing is uploaded: the text stays in your browser.
- 02
Press "Validate JSON"
Press "Validate JSON" or Ctrl + Enter. The result appears below in an instant. Results can be copied.
- 03
Read the result
It appears in the dark panel under the form instantly. Every block has [copy] and other actions.
Key features of this tool
Nothing leaves your browser
The processing is plain JavaScript that runs on your device: the text you paste is never uploaded to our servers or to anyone else.
Instant results
Results appear the moment you press the button, even for long inputs, and every block has copy and download actions.
Works everywhere
No installation, no account and no limits: the tool works on desktop and mobile, in any modern browser, as often as you like.
Frequently asked questions
What makes JSON invalid?
The usual suspects: trailing commas, single quotes instead of double quotes, comments, unquoted keys, missing commas between items, and special values such as NaN or undefined. The validator points out the position and lists the hints that apply.
Is this the same as JSON Schema validation?
No, this checks syntax only (RFC 8259). Schema validation checks that the data has the expected structure and types.
Can I validate very large files?
Documents of several megabytes are fine; the parse runs in your browser and nothing is uploaded.
Are my files or data uploaded?
No. The tool is plain JavaScript that runs in your browser; the files or data you provide here are never uploaded to our servers.