Validation runs entirely in your browser — nothing is uploaded.
Validate JSON5 syntax online, free. JSON5 is a superset of JSON that allows comments, trailing commas and unquoted keys for human-edited config. This validator checks your JSON5 against JSON5 and reports syntax errors with clear messages — processing runs in your browser with nothing uploaded.
It parses your JSON5 and pinpoints syntax errors so you can fix them before they break a build or deploy. 100% free, no registration, and complete privacy — everything runs locally in your browser, so your data never touches a server.
Find JSON5 syntax problems instantly, with messages that point to what needs fixing.
Validation follows JSON5, so a pass means standards-compliant JSON5.
Your JSON5 is parsed locally in JavaScript; nothing is uploaded, logged, or stored.
Unlimited validation with no account or quota, on desktop and mobile.
Paste your JSON5 into the input box and click Validate. The validator runs instantly in your browser and shows the result on the right — no upload, no signup, no installation.
Yes. The JSON5 validator is completely free with no limits, no account, and no watermark. All processing happens locally in your browser for privacy.
No. Your JSON5 never leaves your device — it is processed locally in JavaScript. We don't upload, log, or store your input, so it's safe for proprietary code and config.
It checks your JSON5 for syntax errors and structural validity against JSON5, and reports clear messages pointing to anything that needs fixing.
Yes. The tool is fully responsive and works on phones, tablets, and desktops — just open it in any modern browser.