JSON Validator

A config or API body is either valid JSON or it is not. Paste it here. A successful check prints a single line that the text parsed. A failure is the parser’s own error.

What a green result means

The tool runs JSON.parse and, if that returns, shows that the text is valid JSON. It does not pretty-print, sort keys, or compare two payloads. It also does not check types against a schema. A file can parse and still have the wrong fields for your API. JSON Schema Validator is the separate page where you paste a schema and a document. JSON Formatter is where you go after a clean parse when a human needs indentation.

Errors that fail immediately

Trailing commas, single quotes, comments, and a missing comma between values are invalid JSON even when they are allowed in some config dialects. A sentence pasted above the first brace fails too. The message comes from the browser parser, so it names a position or token rather than a line-numbered code frame. Fix that spot and run it again. JSON Viewer is the pretty view of a document that already parses. JSON Diff compares two documents that both parse.

Secrets in the paste

Validation stays in the tab. That still means the JSON is on the screen. Strip tokens before you share a screenshot of a failure. Very large payloads can make the tab sluggish. For a huge response, validate a reduced sample or the fragment that failed, not a multi-megabyte log with HTML wrapped around it. If the parser points at the start of the text, look for a sentence or a BOM that landed before the first brace.