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UtilDock

JSON Validator

Find the exact line something is rejecting · runs in this tab, never sent anywhere

Document

0 BPaste or drop JSON to validate it

Result

Paste a document into the Document panel. It is checked as you type, entirely in this tab.

How the JSON Validator works

A JSON validator that tells you where the problem is, not just that there is one. Every syntax error is reported with its exact line and column and underlined in the editor. Turn on schema checking and the shape of your data is validated too, against JSON Schema draft 2020-12, 2019-09 or 07. Both the document and the schema stay in this tab.

Every syntax error is reported with its exact line and column, and underlined in the editor where it happens. The parser stops at the first problem, so fix that one and anything further down appears.

Turn on Check against a schema and a second panel opens for a JSON Schema. Every violation is listed with its path, and clicking one jumps the editor to it.

Both the document and the schema stay in this tab. Neither is uploaded, which is the point when the schema is internal and the document is real.

Common questions

Why is my JSON invalid when it looks correct?

The usual causes are a trailing comma after the last item, keys or strings wrapped in single quotes instead of double, an unescaped newline or backslash inside a string, or a stray comment — JSON allows none of those. The validator points at the exact line and column so you can see which one it is.

Which JSON Schema drafts are supported?

Drafts 2020-12, 2019-09 and 07, including the standard format keywords such as date-time, email and uri. Every violation is listed with its path, and clicking one jumps to it in the document.

Is my data or schema sent anywhere?

No. Validation runs as JavaScript in your own tab, so a production payload or an internal schema never leaves your machine. There is no server that could receive it.

Can it validate JSON Lines or JSON with comments?

Not yet — the validator checks strict RFC 8259 JSON, which is what most parsers and APIs accept. JSONC and NDJSON support are on the list.