# How to Format and Validate JSON Without Sending It to a Server

Every developer pastes JSON into an online formatter at some point. The problem is that many of those tools send your data to a server, and API responses often contain tokens, emails, or customer data you shouldn't share.

## Format JSON locally in the browser

A client-side formatter does the work with JavaScript on your machine, so nothing is uploaded. The same thing in plain JavaScript:

```javascript
const raw = '{"name":"Ada","roles":["admin","dev"]}';
const pretty = JSON.stringify(JSON.parse(raw), null, 2);
console.log(pretty);
```

If the JSON is invalid, `JSON.parse` throws an error with the position of the problem, which is how a good formatter can point to the exact line.

## A quick checklist when JSON fails to parse

- Trailing commas after the last item
- Single quotes instead of double quotes
- Unquoted keys
- Comments, which JSON does not allow

## Skip the setup

If you don't want to open a console, the [JSON Formatter on TheTextKit](https://thetextkit.com/tools/json-formatter) validates, pretty-prints, and minifies JSON entirely in your browser, with clear error reporting for invalid input.

Related tools that also run locally:

- [Regex Tester](https://thetextkit.com/tools/regex-tester) to highlight matches and inspect capture groups
- [Base64 Encoder / Decoder](https://thetextkit.com/tools/base64-encoder-decoder)
- [UUID Generator](https://thetextkit.com/tools/uuid-generator)
- [Unix Timestamp Converter](https://thetextkit.com/tools/timestamp-converter)

You can browse all 143 free tools at [thetextkit.com](https://thetextkit.com).

## Takeaway

Treat any text you paste into a web tool as shared unless you know it runs locally. For quick formatting jobs, a browser-only tool keeps your data on your machine.