Catch errors before deploy
Validate config or fixture JSON locally so a stray comma doesn't break a build.
Free · client-side · no sign-up
JSON Validator
Check whether your JSON is valid and get precise, line-and-column error messages for every syntax problem. The JsonLab editor validates as you type — paste your JSON and see issues highlighted instantly.
Use cases
Check API payloads
Paste a request or response body to confirm it's well-formed JSON.
Debug CI failures
Find the exact line and column of a syntax error reported by a pipeline.
Verify hand-edited JSON
Make sure manual edits to a JSON file didn't introduce a structural mistake.
Precise errors
Every syntax error reports the exact line and column, with the offending line highlighted in the editor.
Validate as you type
No submit button — validity updates live while you edit or paste.
Readable diagnostics
Cryptic parser messages are cleaned up into plain, human-friendly explanations.
Format once valid
As soon as your JSON parses, beautify it, explore it as a tree, or minify it in the same editor.
No installs
Runs in any modern browser — nothing to download or configure.
100% private
Validation is local to your browser; your JSON is never sent to a server.
Example
Invalid input
{
"name": "JsonLab",
"tags": ["json", "tools",]
}Reported error
Unexpected token ']' line 3, column 27 Trailing comma after the last array element is not allowed.
How to use it
- 1Open the editor and paste the JSON you want to check.
- 2Valid JSON shows a green status; invalid JSON is flagged with the line and column.
- 3Click the error to jump to it, fix it, and watch the status turn valid.
Frequently asked questions
What does the validator check?
It checks for strict JSON syntax per the JSON spec — correct quoting, commas, brackets and value types — and reports the first error's location.
Why does my JSON with comments or trailing commas fail?
Standard JSON does not allow comments or trailing commas. Remove them to make the document valid.
Is my data sent anywhere?
No. Validation happens entirely in your browser, so nothing is uploaded.
Related tools
JSON Formatter & Beautifier
Beautify and format messy JSON instantly with a VSCode-grade editor. Validate as you type, view as a tree, minify, copy and download — all in your browser.
JSON to CSV Converter
Convert JSON arrays to clean CSV you can open in Excel or Google Sheets.
JSON Diff Tool
Compare two JSON documents and highlight everything that was added, removed or changed.
Ready to go?
No sign-up, no uploads — everything runs in your browser.