JSON Formatter
Pretty print and tidy JSON in your browser.
LocalYour data is processed locally in your browser and is not uploaded to Alphzen.
Paste JSON to format.
Keyboard: Ctrl or Cmd + Enter to format.
How to use
- Paste JSON into the input panel, or load the example.
- Choose an indent size if you want 2 spaces, 4 spaces, or tabs.
- Select Format to pretty print, or Minify to collapse whitespace.
- Copy or download the result. Invalid JSON is explained with a line number.
Features
- Runs entirely in your browser — JSON is not uploaded to Alphzen.
- Pretty print with 2-space, 4-space, or tab indentation.
- Minify in the same workspace when you need a compact payload.
- Syntax errors include line and column so you can fix issues quickly.
- Copy and download formatted output without extra steps.
Examples
{"id":42,"name":"Ada Lovelace","active":true,"roles":["engineer","mathematician"],"profile":{"email":"ada@example.com"}}{
"id": 42,
"name": "Ada Lovelace",
"active": true,
"roles": ["engineer", "mathematician"],
"profile": {
"email": "ada@example.com"
}
}FAQ
Does this JSON formatter send my data to a server?
No. Formatting, minifying, and validation run in your browser with the standard JSON parser. Alphzen does not receive the JSON you paste.
Why is my JSON invalid?
Standard JSON does not allow comments, trailing commas, single quotes, or undefined. The error message includes a line and column pointing at the first problem the parser found.
Can I format JSON with comments (JSONC)?
Not in this tool. JSONC and JSON5 are relaxed dialects. Remove comments and trailing commas, or convert the file to strict JSON, then format it here.
Is there a size limit?
There is no hard upload limit because nothing is uploaded. Very large documents can still slow the tab because parsing and pretty printing happen on the main thread. A warning appears above about 1 MB.
Related guides
- Decoding a JWT is not verifying itReading a JWT payload is debugging. Trusting it requires a signature check with the issuer’s key.
- When JSON to CSV conversion works — and when it does notArrays of objects convert cleanly. Nested trees do not. Learn how flattening, delimiters, and quoting affect the spreadsheet you get.
- How to validate JSON (syntax vs schema)JSON can be well-formed and still wrong for your API. Here is the difference between parse errors and schema checks.
Related tools
About this tool
JSON Formatter on Alphzen pretty prints JSON so nested objects and arrays are readable. Use it when a log line, API response, or config file arrives minified and you need to inspect structure, not when you need a JSON Schema validator.
Formatting is a lossless transform of valid JSON: object key order is preserved, numbers stay numbers, and whitespace is the only thing that changes. If the input is invalid, nothing is rewritten — you get a specific parse error instead of silently broken output.
When you are done reading the document, minify it in the same tool or open JSON Minifier. If you need a spreadsheet, convert arrays of objects with JSON to CSV.