Find out why your JSON will not parse

A single stray comma or missing quote can make an entire JSON document unusable, and error messages from applications are often vague. JSON Validator Pro checks your text against the strict JSON syntax rules and tells you whether it passes. When it fails, it reports the parser's message together with the line and column where it thinks the problem is, and marks that line in a line-by-line view.

Running a check

1. Paste your JSON into the editor. It has line numbers on the left that follow your text as you scroll. Paste reads from the clipboard if the browser permits.
2. To see what the tool does first, click Valid Sample or Error Sample. Either one loads an example and validates it immediately.
3. Click Deep Check & Validate.
4. Read the Validation Report. The header switches between a green JSON Syntax is Valid message and a red Syntax Error Found message, and the Status counter at the top shows VALID or INVALID.
5. For invalid input, read the red card with the error message and the reported Line and Column. In the Annotated Data View, the offending line is highlighted in red.

For valid input the report also shows Depth (levels of nesting), Keys (total property names across all objects) and Size in bytes, KB or MB.

Helper buttons under the editor

• Format re-indents valid JSON with four spaces in place.
• Minify collapses valid JSON to one line in place.
• Smart Fix applies two simple repairs: it removes trailing commas before a closing bracket or brace, and wraps bare keys in double quotes. It then validates again.

Format and Minify refuse to work on invalid input and show a message telling you to fix the errors first.

Situations where it helps

• Debugging a configuration file that an application refuses to load.
• Checking a hand-written request body before sending it to an API.
• Cleaning up JavaScript-style object literals pasted from code, which often have unquoted keys and trailing commas.
• Confirming that exported data is well-formed before importing it elsewhere.

Caveats

Validation checks syntax only. It does not compare the data to a schema or confirm that values make sense. The line and column come from the browser's error message, whose wording and detail differ between browsers, so treat them as a pointer and look at the lines just above too, since the real mistake often occurs before the place where parsing gives up. Smart Fix uses simple pattern matching and cannot handle single-quoted strings, comments or missing brackets, and it may alter text inside strings that happens to look like a key. Everything runs in your browser via JavaScript. The Copy button in the report copies the current editor content.

Related Tools

• Config File Formatter
• Csv To Json
• Env Formatter
• Json Formatter