JSON Validator
Validate JSON and locate syntax errors
What is JSON Validator?
JSON Validator is a free developer utility from Farvixo that lets you validate JSON and locate syntax errors. Your input is processed locally in the browser — nothing is sent to a server, which matters when the payload is a token, a config file or production data. Free, unlimited, no sign-up.
How to use JSON Validator
Paste your snippet into JSON Validator. It stays on your device, which matters when you are handling tokens, config or production data.
JSON Validator processes the input instantly and points at the exact line when something is malformed, so you can fix it rather than hunt for it.
Copy the result to your clipboard or download it. Free, unlimited and no sign-up.
Frequently Asked Questions
My JSON looks fine but will not parse. Why?
Three causes account for almost every case: a trailing comma after the last item, smart quotes pasted from a document or chat app instead of straight quotes, and an unescaped backslash or newline inside a string. The reported position points just after the real mistake.
Are comments allowed in JSON?
No. The JSON specification has no comment syntax, which surprises people coming from JavaScript. Some parsers accept them as an extension, but a file with comments is not valid JSON and will fail elsewhere.
Is it safe to paste a real API response?
Yes. Validation happens entirely in your browser — there is no request carrying your data and nothing is logged. That is the point of building it this way.
What is the difference between valid and correct?
This checks syntax, not meaning. JSON can be perfectly valid and still have the wrong field names or types for the API you are sending it to. Validate against a schema for that.
Can it format as well as validate?
Yes — valid JSON can be pretty-printed with consistent indentation, or minified. Formatting is often what makes a structural error obvious in the first place.
What you can use JSON Validator for
- Inspecting or reformatting an API payload while debugging
- Decoding a token or encoded value without pasting it into an unknown website
- Generating test data or identifiers during development
- Validating a config file before it is committed or deployed
JSON Validator at a glance
- Tool
- JSON Validator — Developer Tools
- Purpose
- Validate JSON and locate syntax errors
- Input
- Text or values you enter directly
- Output
- Processed output you can copy to the clipboard or download
- Processing
- In your browser — files are never uploaded to a server
- Price
- Free, unlimited, no account required
- Limitations
- Bounded by your device's memory and CPU rather than a server quota
Tips for better results
- Because processing is local, it is safe to paste real credentials or production payloads here — nothing is transmitted or logged.
- When parsing fails, the reported line and column point at the first invalid token, which is usually just after the real mistake.
- Bookmark the tool page directly; it loads without an account and works offline once cached.
Common problems and how to fix them
Parsing fails on valid-looking input
Usually a trailing comma, a smart quote pasted from a document, or an unescaped backslash. Check the reported position first.
Output has unexpected whitespace or line endings
The source used CRLF line endings or a non-breaking space. Normalise the input before processing.
Non-English characters come out wrong
The input was not UTF-8. Re-save the source as UTF-8 and paste it again.
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