How to Format and Validate JSON Online

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Raw JSON from an API or log file usually arrives as one long, minified line that is almost impossible to read. Formatting (also called beautifying or pretty-printing) adds indentation and line breaks so the structure becomes clear. Validating confirms the JSON is well-formed before you rely on it. Here is how to do both online, for free, with JSON Wallet.

What formatting and validating actually mean

Formatting does not change your data — it only changes the whitespace, so the same object is easier for a human to read. Validating checks that the text obeys the JSON grammar: every string quoted, every bracket balanced, no trailing commas. A document can be valid but ugly (minified), or readable but invalid (a pretty-printed file with one stray comma). You usually want both: valid and readable.

Step 1: Paste your JSON

Open the editor and paste your JSON into the input panel. It works with anything from a tiny object to multi-megabyte API responses, and nothing is uploaded — the JSON is processed entirely in your browser, which makes it safe for sensitive payloads.

Step 2: Format it

As soon as valid JSON is detected it is pretty-printed automatically, but you can also click Format to re-indent at any time. A minified line like this:

{"id":1,"tags":["a","b"],"meta":{"ok":true}}

becomes readable:

{
  "id": 1,
  "tags": ["a", "b"],
  "meta": {
    "ok": true
  }
}

Step 3: Validate

JSON Wallet shows a live Valid / Invalid badge as you type. When the JSON is invalid, it tells you the exact line and character position of the first error, so you can jump straight to the problem instead of hunting for it. If you are not sure what an error means, our guide on common JSON errors explains each one.

Step 4: Explore with tree and table views

For large or deeply nested data, switch to Tree view to expand and collapse objects and arrays interactively, or Table view to scan arrays of records like a spreadsheet. This makes it much easier to find the one field you care about in a response with hundreds of properties.

Step 5: Minify when you are done

When you need to put the JSON back into code or send it over the wire, click Minify to strip all the whitespace and collapse it back to a single compact line. Minified JSON is identical data — just smaller, which matters for network payloads and storage.

Beyond formatting: repair, diff and transform

JSON Wallet is more than a pretty-printer. If your input is broken, the Repair tool fixes common mistakes automatically. If you need to spot what changed between two payloads, paste them into the two panels and use Compare to see a line-by-line diff. And the transform tools handle stringify, escape, Base64 and URL encoding without leaving the page.

Why do it in the browser?

Because JSON Wallet runs entirely client-side, your data never touches a server. That makes it safe to format and validate sensitive payloads — API responses with tokens, internal configs, customer records — without worrying about where the data goes. Read more about that in our Privacy Policy.

Frequently asked questions

Does formatting change my data?

No. Formatting only adds or removes whitespace. The keys, values, and structure are identical before and after — only readability changes.

Is it safe to paste sensitive JSON?

Yes. JSON Wallet processes everything in your browser and sends nothing to a server, so tokens, credentials and customer data never leave your device.

What indentation does it use?

Two-space indentation by default, which is the most common convention for JSON. You can re-minify at any time to remove indentation entirely.

Keep reading

Ready to put this into practice? Open the free JSON editor →