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JSON Validator

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Code & Dev

JSON Validator

Validate and format JSON data.

Workspace

Run the tool here

Browser utility

Output

Run the workspace to see the response here.

How to use

Paste the JSON.
Run the validator.
Fix the reported error and re-run until valid.

About this tool

Validate JSON syntax and pinpoint the line and column of the first error.

JSON Validator is part of the TmpMailer Code & Dev set — free browser utilities that open instantly, need no account, and pair well with a temporary-email workflow when you just need a quick result.

Common use cases

Checking a config file before deployment.
Debugging an API payload.
Verifying generated JSON in a test.

Common questions

Does valid JSON mean valid data?

No. Syntax and schema are separate. A payload can be valid JSON and still miss required fields.

Why is a trailing comma an error?

JSON does not allow trailing commas, even though JavaScript object literals do.

Can it validate very large files?

Browser memory limits apply. Use a streaming validator for multi-megabyte payloads.

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