FreeDev Tools

JSON Validator

Validate JSON syntax and get a structure report — root type, node count, depth, and byte size.

Runs locally in your browser. Your input is not uploaded.

How to Use

  1. 1

    Paste your JSON

    Paste the JSON you want to check into the input panel.

  2. 2

    Read the verdict

    Valid JSON gets a green report with structure stats. Invalid JSON gets the parser error with line and column.

  3. 3

    Fix and re-check

    Correct the reported issue and the validator re-runs instantly as you edit.

Frequently Asked Questions

It checks that your input is syntactically valid JSON per RFC 8259 — balanced braces, quoted keys, legal values, and no trailing commas. Valid input also gets a structure report: root type, node count, nesting depth, and byte size.

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