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Format JSON

Validate and indent JSON without rewriting its number tokens.

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Max 100 MB per file · JSON

    Text options

    UTF-8 files only. Up to 300,000 characters per file.

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    Free No watermark No sign-up Files never uploaded
    Invalid JSON?You get a clear message about the wrong comma, quote or bracket.
    Want a table?Use JSON to Excel.
    Need it small again?Use Minify JSON.

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    How to use Format JSON

    1. Select your JSON files.Add compressed or messy JSON files up to 2 MB.
    2. Choose the indent spaces.Pick how many spaces to use for each level.
    3. Click Format JSON.Save the readable JSON — the data itself is unchanged.
    4. Check the data.It is easier to read, and the data is unchanged.

    About Format JSON

    When is it useful? Format JSON makes compressed or messy JSON readable by adding line breaks and indentation — useful when checking API responses, configuration files and data exports.

    Good to know: the JSON is checked first, and if a comma, quote or bracket is wrong you get a clear message. Choose 2, 4 or 8 spaces of indentation. Numbers are kept exactly as written — large IDs are not rounded — and duplicate keys are not removed. Files up to 2 MB are supported.

    Tips for Better Results

    • Use 2 spaces for web projects and 4 for easier reading.
    • To shrink the file again, use Minify JSON.
    • To see the data as a table, use JSON to Excel.

    Frequently Asked Questions

    Will large IDs be rounded?
    No. Numbers are kept exactly as written.
    Which indentation should I pick?
    2 spaces for web projects, 4 for easier reading, or 8.
    Are duplicate keys removed?
    No. Duplicate keys are not removed.
    Works with: VS Code · Notepad++ · most text and code editors

    What converts well, and what doesn't

    SettingResult
    Indentation2, 4 or 8 spaces
    JSON checkDone first
    NumbersKept exactly — large IDs not rounded
    Duplicate keysNot removed
    File sizeUp to 2 MB
    💡 Tip: Use 2 spaces for web projects and 4 for easier reading.

    Common uses

    API responsesRead them easily.
    Config filesCheck settings.
    Data exportsInspect data.
    DebuggingFind errors.
    LearningUnderstand JSON.
    SharingReadable files.

    Is my file safe?

    Browser processing: your files are processed on your own device and are never uploaded to our server.

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    Guide

    Format JSON: a complete guide

    Why format JSON

    JSON from APIs and apps is usually minified — one long line without spaces — which is impossible to read. Formatting adds line breaks and indentation so you can see the structure, check values, find errors and explain the data to others.

    How it works

    Upload a .json file of up to 2 MB. It is first checked to be valid JSON; if a comma, quote or bracket is wrong, you get a clear message. Then it is rewritten with each item on its own line and nested items indented by 2, 4 or 8 spaces.

    What is preserved exactly

    Unlike many formatters, this tool does not re-parse and rewrite values: numbers stay exactly as written (large IDs are not rounded and 1.50 stays 1.50), duplicate keys are not removed, and key order is unchanged. Only whitespace is changed.

    Common problems and how to fix them

    “Invalid JSON”: common causes are a trailing comma, single quotes instead of double quotes, or comments, which JSON does not allow. Very deeply nested data stops at 100 levels: such files are unusual — check the source. The output is large: formatted JSON is bigger; use Minify JSON to shrink it again.

    Good habits

    Format JSON before reviewing or editing it, minify it again for production use, and keep the original file.

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