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  1. Home
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  4. /JSON Validator

Developer Tools

JSON Validator

Validate JSON syntax and inspect key counts instantly.

Tip: Cmd/Ctrl+Enter for the primary action · drafts save locally

Cmd/Ctrl+Enter validates.

About this tool

Confirm whether a payload is valid JSON before sending it to an API or committing config. Get pass/fail status and helpful error details.

How to use

  1. Paste the JSON string.
  2. Click Validate.
  3. Review the status message and fix any reported issues.

Examples

  • Validate a webhook body before posting.
  • Check a theme config file for trailing commas.
  • Confirm an LLM output is valid JSON.

Benefits

  • Clear pass/fail feedback
  • Line, column, and path hints
  • Key count insights
  • Private and fast

Frequently asked questions

Why is my JSON invalid?+

Common issues include trailing commas, single quotes, comments, and unquoted keys — none of which are allowed in standard JSON.

Can I format after validating?+

Yes. Use our JSON Formatter to beautify valid JSON.

How do I find the exact line causing invalid JSON?+

Paste your payload into ToolVera’s JSON validator. When parsing fails, the error message points to the problem so you can fix commas, quotes, or brackets quickly.

Does JSON allow comments or trailing commas?+

Standard JSON does not. Remove // comments, /* blocks */, and trailing commas after the last property or array item before validating.

Related guide

Catch trailing commas, bad quotes, and broken braces instantly. Free browser JSON validator from ToolVera — no uploads required.

Read: Validate JSON Online Before You Deploy →

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