JSON Formatter
Format, validate, and minify JSON locally in your browser.
JSON Formatter cleans up messy or minified JSON so you can read, validate, and share structured data quickly. Paste any JSON payload, format or minify it locally, and copy or download the result without sending data to a server.
How it works
The tool parses your input with the browser JSON parser. If parsing succeeds, it re-serializes the value with your chosen indentation (or as compact JSON when minifying). Validation uses the same parser and surfaces the first syntax error when the input is invalid.
Benefits
- Runs fully in the browser with no upload step
- Formats and minifies with a single click
- Clear parse errors instead of silent failures
- Copy, download, share, and reset actions built in
Use cases
- Pretty-print API responses while debugging
- Clean minified config files before editing
- Validate JSON pasted from logs or tickets
- Prepare compact JSON for request bodies
Best practices
- Validate before formatting when the source is untrusted or noisy
- Prefer 2-space indentation for diffs and code review
- Minify only after you confirm the structure is correct
- Clear the workspace before pasting secrets on shared machines
Common mistakes
- Using single quotes around keys or strings
- Leaving trailing commas after the last property
- Including // or /* */ comments, which JSON does not allow
- Pasting multiple JSON values without wrapping them in an array
Privacy
All parsing happens in your browser. ToolHub does not receive your JSON for this tool. Optional LocalStorage favorites/recents store only tool slugs you choose—not the JSON content—unless you separately enable on-device history.
Frequently asked questions
- Does the JSON Formatter upload my data?
- No. Formatting and validation run entirely in your browser. Your JSON never leaves your device for this tool.
- What does Format do versus Validate?
- Validate checks whether the input is valid JSON and reports parse errors. Format parses the JSON and reprints it with indentation so it is easier to read.
- Can I minify JSON as well?
- Yes. Use Minify to remove unnecessary whitespace and produce a compact single-line JSON string suitable for APIs or storage.
- Why did I get a parse error?
- JSON is strict: property names must use double quotes, trailing commas are not allowed, and comments are invalid. The error message points to the first problem the parser found.
- Is my JSON stored in LocalStorage?
- Not by default. Optional device history can remember recent inputs if you enable it. This tool is not marked sensitive, but you should still avoid saving secrets on shared computers.
- Does formatting change my data?
- Formatting only changes whitespace and key order as produced by JSON.stringify. Values, types, and structure stay the same for valid JSON.
- Can I download the formatted result?
- Yes. Use Download to save the current output (or input if you have not formatted yet) as a .json file on your device.
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