Paste JSON and find out immediately whether it is valid — with the exact position of the first error — then pretty-print or minify it. Runs in your browser, nothing uploaded. Free, no account needed.
Paste the JSON and the validator reports either "valid" or the precise character where parsing failed — a trailing comma, a single-quoted string, a missing bracket. Fix it, re-check, and format or minify the result.
Validation uses the browser's strict native parser, so if it passes here it will pass in production. Nothing is uploaded.
Standard JSON forbids a comma after the last element of an object or array, even though JavaScript allows it.
No — JSON strings and keys must use double quotes.
No, validation happens in your browser.
JSON Minifier · JSON Formatter & Validator (all features)
Free, private, no account. Like every DevForge tool, this one runs in your browser and never uploads your files. See all 35 free tools or join the DevForge community to share your own games, tools and assets.