Developer tool
JSON Validator
Paste JSON to check whether it parses, find syntax errors, and copy a beautified or minified version after it passes validation.
Validate JSON before you use it
Request bodies, webhook payloads, config snippets, and copied API responses often fail because of one small syntax issue. Paste the JSON to check it with the browser parser and see the error near the tool.
When the JSON is valid, you can beautify it for review or minify it for a compact payload. The data stays in your browser.
Practical examples
- API responses: Copy a response from an API client, browser DevTools, or a server log to confirm that a parse error comes from invalid JSON.
- Config files: Check
package.json, an application config, or a JSON config snippet before committing or deploying it. - Request bodies and webhooks: Validate a Postman request body or webhook payload before sending it or while debugging a failed request.
Common JSON syntax errors
- Trailing commas:
{"name":"NimbleTools",}is invalid; remove the final comma to get{"name":"NimbleTools"}. - Missing property-name quotes: JSON requires double quotes around names, so use
{"active":true}instead of{active:true}. - Unclosed or mismatched braces and brackets: Every object and array delimiter needs a matching closing character.
- Invalid characters in strings: Double quotes, backslashes, and control characters inside a string must use valid JSON escapes.
If the JSON is malformed in several places, JSON Repair can try to fix common structural and quoting problems.
Related JSON tools
Use the JSON Formatter for a combined formatting workflow, the JSON Viewer to inspect a tree, or the JSON Compare tool when two payloads need to be checked side by side.
FAQ
Is my JSON sent to a server?
No. Validation, formatting, and minifying run locally in your browser. Pasted API keys, tokens, and config values are not sent to a server for validation.
What errors can the validator show?
It reports browser parser errors for problems such as trailing commas, missing or mismatched quotes, unclosed braces or brackets, and invalid escapes. When the browser provides a character position, the tool also shows the corresponding line and column.
Can it validate JSON schema rules?
No. This page checks whether the text follows JSON syntax and can be parsed. It does not validate values against a JSON Schema document.
Can I copy valid JSON after checking it?
Yes. Beautify or minify the JSON, then copy the result.
Does beautifying change the data?
No. Beautifying and minifying only change whitespace and presentation; they do not change JSON keys, values, or structure.
How do I know if my JSON is valid?
Paste the JSON and select Validate. A valid result shows the root type; an invalid result shows the parser error so you can correct the syntax.
Can I validate JSON from an API response or webhook payload?
Yes. You can paste an API response, webhook payload, request body, or JSON copied from a server log and check it before using it elsewhere.
What is a JSON syntax error?
A JSON syntax error means the text does not follow JSON grammar, such as a trailing comma, missing quote, invalid escape, or unclosed brace.