Free JSON Formatter & Validator
100% Private · No Uploads · No Account
Format, validate, and explore JSON and XML entirely in your browser. Pretty-print, minify, sort keys, browse with tree view, or view arrays as a table — your data never leaves your device.
When You Need a JSON Formatter
Debugging API Responses
Paste a minified API response from Postman or curl and instantly read it. The Tree View lets you collapse large nested objects and focus on the fields that matter.
Reviewing Sensitive Configs
AWS credentials, database configs, and JWT payloads must stay off public servers. This tool runs 100% in your browser — nothing is transmitted or logged anywhere.
Normalising JSON for Diffs
Use "Sort Keys A→Z" before running a diff so key-ordering differences don't show up as false positives. Produces consistent, canonical output every time.
Reading Tabular API Data
When an API returns an array of records, Table View turns it into a familiar spreadsheet layout instantly — no CSV export, no Excel, no copy-paste required.
Why Privacy Matters for a JSON Formatter
| Feature | SimpleTool | Tool A | Tool B |
|---|---|---|---|
| Data stays in your browser | ✅ | ❌ Server-side | ⚠️ Unclear |
| No account required | ✅ | ✅ | ❌ |
| Tree view | ✅ | ✅ | ✅ |
| Table view (arrays) | ✅ | ❌ | ❌ |
| Sort keys | ✅ | ❌ | ✅ |
| XML support | ✅ | ✅ | ❌ |
| No ads, no rate limits | ✅ | ❌ Ads | ❌ Rate limits |
Frequently Asked Questions
Does my JSON or XML get sent to a server?
No. Everything runs in your browser using JavaScript's native JSON.parse and the browser's DOMParser. Your data never leaves your device — there are no server requests for formatting or validation.
What is the difference between Format and Minify?
Format (pretty-print) adds indentation and line breaks to make JSON or XML human-readable. Minify removes all insignificant whitespace to produce the smallest possible output — useful for API payloads, config files, and reducing transfer size.
What does "Sort Keys A→Z" do?
It recursively sorts every object's keys in alphabetical order throughout the entire JSON document. Useful for canonical serialization, diffing two JSON blobs, and keeping config files consistent across teams.
What is the Tree View?
Tree View renders the parsed JSON as a collapsible, interactive tree. Click any object or array node to expand or collapse it. Nodes deeper than 3 levels start collapsed to keep the view manageable for large documents.
When does the Table View appear?
Table View is automatically available when the root of your JSON is an array of objects (e.g., an API response that returns a list of records). Each unique key across all objects becomes a column header, and each element becomes a row. Up to 500 rows are shown.
What kinds of JSON syntax errors are detected?
The validator catches all standard JSON syntax errors: trailing commas, missing quotes around keys, single-quoted strings, comments, unescaped characters, and mismatched brackets. On Firefox, the error indicator shows the exact line and column of the problem.
Does the tool support large JSON files?
Yes. Because everything runs locally in your browser, there is no upload size limit. The formatter handles files of any size as long as your browser tab has enough memory. Very large JSON (tens of MB) may slow down the Tree View — use the formatted text view for those.
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