What is the JSON Validator?
Validate JSON syntax with clear error locations. The JSON Validator is a free online tool that works instantly in your browser — no installation, no signup and nothing to upload. It sits alongside other JSON & Data tools on DevNibble such as JSON Formatter, JSON Minifier, JSON Viewer.
How to use the JSON Validator
- Paste your data into the input.
- Any errors are highlighted instantly with the exact location.
- Fix the issues and re-validate.
Features
- Runs 100% in your browser — your data is never uploaded or stored.
- Free forever, with no account, no ads and no tracking.
- Copy or download your result in one click.
- Fast and responsive on desktop, tablet and mobile.
Frequently asked questions
What does the JSON validator check?
It validates your text against the strict JSON syntax in the ECMA-404 / RFC 8259 standard and points to the exact line and column of any error.
Does it fix invalid JSON?
The validator reports errors; use the JSON Fixer tool to automatically repair common mistakes like trailing commas or single quotes.
Is it free and private?
Yes — validation runs in your browser and nothing is uploaded.