FreeDev Tools

JSON Size Analyzer

Break down the byte size of each key in a JSON document — find what makes your payload heavy.

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

How to Use

  1. 1

    Paste your JSON

    Use a real API response or config document.

  2. 2

    Read the breakdown

    Keys are sorted by size with bytes, percentage, and a bar per key.

  3. 3

    Optimize the heavy fields

    Trim, paginate, or lazy-load the fields that dominate the total.

Frequently Asked Questions

The minified byte size of each top-level key (or array element), with percentages and a bar chart, so you can see exactly which fields make your payload heavy.

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