JSON Formatter
Validate JSON in the browser, or pretty-print and minify via Toolomix servers using System.Text.Json.
JSON Successfully Processed
Your JSON has been formatted and validated successfully
JSON Validation Failed
Please check your JSON syntax and try again
Tips
Validate before formatting
Use Validate Only first to catch syntax errors in the browser without sending data to the server.
Pretty Print and Minify use the server
Those actions POST your text to Toolomix endpoints that re-serialize with System.Text.Json.
Fix errors yourself
The tool reports invalid JSON; it does not rewrite or auto-repair broken syntax.
Validate Only in the browser
Runs JSON.parse locally so you can check syntax without a pretty/minify server call.
Pretty Print on the server
Posts to /web-tools/PrettyJson and returns indented JSON via System.Text.Json WriteIndented true.
Minify on the server
Posts to /web-tools/MinifyJson and returns compact JSON with WriteIndented false.
What this tool does
JSON Formatter helps you check pasted JSON and optionally reformat it for readability or compactness.
Validate Only runs in the browser. Pretty Print and Minify send the text to Toolomix and return System.Text.Json output.
How to use
Paste your JSON
Add the JSON text into the input field (primary input is pasted text).
Choose an action
Validate Only for a local syntax check, Pretty Print for indented output, or Minify for compact output.
Review, copy, or download
Inspect the result, copy it, or download the formatted JSON when available.
Supported inputs and output
Input: pasted JSON text (objects, arrays, and nested combinations of valid JSON values). Output: the same logical document, either unchanged (validate), indented (pretty), or compact (minify).
This is not a PDF or binary file converter and does not rely on the ~100 MB file-upload middleware used by converter tools.
Processing and privacy
Validate Only uses JSON.parse in your browser and does not call PrettyJson or MinifyJson.
Pretty Print and Minify POST your text to Toolomix (/web-tools/PrettyJson and /web-tools/MinifyJson). That data is sent to Toolomix servers for those actions—not processed only in the browser. See the Privacy Policy for how requests and logs are handled.
Limitations
Known limits
- Does not auto-fix or rewrite invalid JSON
- Pretty Print and Minify require a successful server response
- Primary input is pasted text, not a dedicated multi-file upload flow
- Non-JSON text (for example trailing commas or comments) will fail validation
Troubleshooting
If validation fails, check for trailing commas, single quotes, unescaped characters, or incomplete braces and brackets.
If Pretty Print or Minify fails after a successful Validate Only, retry the request and read the on-page error—those actions depend on the Toolomix endpoints responding successfully.
Frequently Asked Questions
What is the difference between Validate Only, Pretty Print, and Minify?
Validate Only parses in your browser with JSON.parse and does not reformat. Pretty Print and Minify send the text to Toolomix and re-serialize with System.Text.Json (indented or compact).
Is my JSON always processed only in the browser?
No. Validate Only stays client-side. Pretty Print and Minify POST your content to Toolomix servers and return the result.
Will it auto-fix invalid JSON?
No. Invalid JSON is rejected with an error message. You must correct the syntax yourself.
Do I upload a .json file?
The primary workflow is pasting text into the input area. Pretty and minify operate on that pasted string.
What library formats the output?
Server pretty-print and minify use System.Text.Json with WriteIndented set to true or false.
Does it support nested objects and arrays?
Yes, as long as the text is valid JSON—objects, arrays, nested structures, strings, numbers, booleans, and null.
Why did Pretty Print fail while Validate Only seemed fine?
Validate Only uses the browser parser. Pretty Print also requires a successful server round-trip; network or server errors can fail even when local parse succeeded—retry or check the error message shown.
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Paste JSON, validate locally, or pretty-print and minify on Toolomix.
