json0 vs JSON formatter sites
Formatter sites such as jsonformatter.org pretty-print in the browser but load dozens of ad and tracking services, and their save feature can make your JSON public. How json0 compares, and where the big formatter sites are still the better pick.
Short answer: for pretty-printing or minifying JSON, all the popular formatter sites do the job, and the biggest one, jsonformatter.org, formats in your browser. The differences are what else the page does. jsonformatter.org loads a large advertising stack and offers to save your JSON online, which makes it public unless you log in. json0 formats the same way, loads nothing from other hosts, and has no save-online feature to leak through. Pick jsonformatter.org when you need one of its hundred-odd other formatters and converters.
At a glance
| json0 Format | jsonformatter.org | |
|---|---|---|
| Formats in the browser | Yes | Yes ("Your JSON Data gets validated in the browser itself") |
| Indentation | 2 spaces, 4 spaces or tabs | 2, 3 or 4 spaces |
| Minify | Yes | Yes |
| Sort keys | Yes | A separate JSON Sorter tool |
| Escape / unescape JSON as a string | Yes | A separate Stringify tool |
| Size before and after | Yes | No |
| Tree view | No | Yes |
| Suggested fixes for errors | No | Yes |
| Save online and share | No (JSON Diff share links keep the data in the URL fragment) | Yes; public unless you log in |
| Remembers your last JSON | No | Yes, in local storage |
| Ads | None | Yes (Google advertising) |
| Analytics | None | Google Analytics and Clicky |
| Other hosts contacted when the page loads (our test) | 0 | 60 |
| Account | None | Optional login for private links |
Where your data goes
jsonformatter.org says it validates your JSON in the browser, and in our test none of its requests carried the JSON we pasted. Two things are still worth knowing.
The page itself talks to a lot of other services. When we loaded jsonformatter.org once in headless Chrome on 25 October 2026, it made 152 requests to 60 other hosts: Google's ad and analytics services, header bidding exchanges, identity and audience services. It also set more than a dozen cookies before we did anything. Its privacy policy names Google Analytics and Clicky for analytics and says Google may use the data it collects to personalise ads. The same test on json0.dev made 14 requests, all to json0.dev itself.
The save button publishes. jsonformatter.org can save your JSON online with a title, tags and an expiry. Its own page says: "If JSON data is saved without login, it will become public." Its policy adds, in capitals: "DO NOT SAVE SENSITIVE DATA USING THE SAVE FUNCTIONALITY." That is honest of them, and it is also the easiest way for a production payload to end up on the open web. json0 has no save-online feature: the only way to share is a JSON Diff link, which carries the documents in the part of the URL after #, which browsers do not send to the server.
The site also keeps the last JSON you formatted in your browser's local storage, so the next person on a shared computer may see it. json0 stores only your theme setting.
Formatting itself
Both produce the same output for the same settings; JSON formatting is not where tools differ much. json0's Format adds a few things that help when you are working with payloads rather than just reading them:
- Sort keys while formatting, so two versions of a document line up for a text diff.
- Escape as a string and unescape, for JSON that has to travel inside another JSON value, an environment variable or a log line, and back again.
- Size before and after, so you know what minifying saves: json0's sample invoice goes from 621 bytes minified to 836 bytes pretty-printed.
- Use output as input, to chain steps without copying.
jsonformatter.org has a tree view, which is nicer than plain text for exploring a large unfamiliar document, and suggested fixes for common syntax errors.
Where jsonformatter.org is stronger
- Breadth. Formatters and validators for XML, YAML, HTML, CSS, JavaScript, TypeScript, SQL and more; converters between JSON, XML, CSV, YAML and TSV; JSON to classes in about twenty languages; a JSON5 formatter.
- Tree view and image previews for exploring a document.
- Loading from a URL with a
?url=parameter, and file upload. - Saving online, if you need a hosted copy and the data is not sensitive.
Where json0 is stronger
- No ads, analytics, cookies or third-party requests, and a privacy page that lists every request the site can make.
- Nothing to leak by accident: no save-online button, no copy of your last document left in the browser.
- The work after formatting: compare two versions by path, query with JSONPath, turn an array into a table and copy it as CSV, infer a schema, TypeScript and Zod, or redact secrets before you paste the payload anywhere else.
- MongoDB tools for Extended JSON, ObjectIds and testing find filters without a database.
Which to use
- Formatting a document that came from a customer, a production log or an API key holder: json0, or any formatter you can run offline.
- Converting between many formats, or generating classes in a language json0 does not cover: jsonformatter.org, with nothing sensitive in the input.
- Sharing a document with a colleague: not a public paste. Send the file, or for a comparison, a json0 Diff link.
How we tested
On 25 October 2026 we opened each site once in a fresh headless Chrome profile, from India, without accepting any consent prompt, and recorded every network request for six seconds after the page loaded. Then we put a JSON document containing a unique marker string into the editor, formatted it, and recorded requests for another six seconds, checking whether any request URL or body contained the marker. Advertising stacks change by country, consent and day, so your numbers will differ; the method is what to repeat.
Frequently asked
Is jsonformatter.org safe for sensitive JSON? It says formatting happens in the browser, and in our test the pasted JSON was not sent anywhere. Do not use its save feature for anything sensitive; its own policy says the same. If your rules forbid third-party scripts on pages that handle customer data, use a tool that loads none.
Does json0 have a tree view? Not yet. The JSON Crack comparison covers a good free viewer, and you can request a feature.