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JSON Formatter & Validator: How to Read and Debug JSON

How to format, validate and minify JSON — what common JSON errors mean and how to fix them — for developers and beginners.

15 June 2026·5 min read·Open the tool →

What is JSON?

JSON (JavaScript Object Notation) is a lightweight data format used by virtually every web API, config file, and database export. Minified JSON with no whitespace is nearly impossible to read by eye.

How to format JSON

  1. Open ToolCrix JSON Formatter.
  2. Paste your raw/minified JSON.
  3. Click Format — it adds proper indentation and line breaks.
  4. Use the tree view to collapse/expand nested objects.

Common JSON errors

  • Unexpected token — trailing comma after the last item. JSON doesn't allow trailing commas.
  • Unterminated string — missing closing quote.
  • Expected property name — object keys must be in double quotes (not single).
  • Unexpected end of input — an unclosed bracket or brace.

When to minify JSON

Before embedding in production code or API payloads. A 100KB formatted JSON can become 60KB minified.