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Tool Factory

Structured Data

JSON Validator

Check whether text is strict JSON or JSON Lines in your browser. Errors name the exact line, column, and cause, such as a trailing comma.

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Add the required input to continue.

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You can run the tool again after any change.

Your result appears here

Check whether text is strict JSON or JSON Lines in your browser. Errors name the exact line, column, and cause, such as a trailing comma.

This tool runs open-source code from OmniTools (MIT License). See open-source credits.

The validator tries one complete JSON document first. If that fails, it checks each nonblank line as a separate record.

The result reports valid and format. A failure includes the first error location and its cause.

  • Confirm that a hand-edited config file is strict JSON before a deploy.

Sources: RFC 8259: JSON syntax

Check two JSON Lines records

Input: {"id":1,"done":true} {"id":2,"done":false}

Settings: None. This tool has no options.

Result: { "valid": true, "format": "jsonl" }

Both records pass individually, so the result identifies JSON Lines.

Read syntax errors without assuming schema validity

  1. Paste the text into JSON input.
  2. Read format to distinguish json from jsonl.
  3. Fix the reported line and column, then check the input again.
  • A syntax pass does not check JSON Schema or application rules.
  • An endpoint that accepts one document can reject JSON Lines.