JSON Validator

JSON

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Settings

JSON Validator runs on your device

Runs in your browser

No uploads.There is no file-upload endpoint on duck.tools. This tool process your input inside this browser tab.
No tracking.No analytics and no tracking cookies. Sign-in uses a session cookie and loads Cloudflare Turnstile only when you open the account dialog.
We never see your data.Your file never reaches a Duck Tools server, so there is nothing for us to store, read or leak.

Validation happens in this page with the built-in JSON parser. Nothing is sent anywhere.

To be precise: your browser still downloads this page, its scriptsover the network, and our web server keeps standard access logs. What never travels is the content you put into a local tool.

Read the full privacy page →

Your account

No password. We email you a sign-in link.

Human check

Saving presets across devices is next. For now this just signs you in.

How we handle your email

JSON Validator

Check JSON syntax and see the line, column and a short hint.

Paste JSON to confirm it parses. When it does not, we show the line and column, a snippet around the failure, and a hint for common mistakes such as trailing commas or single quotes. Nothing is uploaded.

How it works

Paste JSON or open a file in the editor.
Valid documents show type, depth and how many nodes they contain.
Invalid JSON shows the line, a snippet and a hint when we recognise the mistake.

Also known as

json
validate
syntax
errors
lint
parse

Related tools

JSON FormatterPretty-print JSON and inspect it as text or a collapsible tree.
JSON DesignerBuild JSON structures and datasets from a visual editor, then copy the result.
JSON DiffCompare two JSON documents and list added, removed and changed paths.

LOCALRuns in your browser

No uploads.There is no file-upload endpoint on duck.tools. This tool process your input inside this browser tab.
No tracking.No analytics and no tracking cookies. Sign-in uses a session cookie and loads Cloudflare Turnstile only when you open the account dialog.
We never see your data.Your file never reaches a Duck Tools server, so there is nothing for us to store, read or leak.

Validation happens in this page with the built-in JSON parser. Nothing is sent anywhere.

To be precise: your browser still downloads this page, its scriptsover the network, and our web server keeps standard access logs. What never travels is the content you put into a local tool.

More json tools →Full privacy page →