Developer Tools

These are the small jobs that interrupt real work: a JSON payload that will not parse, a token you need to read the claims from, a string that arrived Base64-encoded, a regular expression that nearly works. None of them is worth opening an editor for, and none of them should require handing your data to a stranger.

Every tool here runs in your browser. The JSON formatter reports the exact line and column of a syntax error using its own scanner, because browsers word their parse errors differently and none of them is reliable to quote. The JWT decoder reads a token without ever claiming to have verified it. The regex tester runs your pattern in a background worker, so a pattern that backtracks catastrophically gets stopped instead of freezing the tab.

The rest of the set covers the jobs that sit either side of those: hashing a file to check a download against its published checksum, encoding a value for a URL or escaping one for HTML, formatting a query that arrived from an ORM as a single enormous line, and comparing two versions of a file line by line to find the one character that changed. Each is deliberate about the thing it is easy to get wrong — MD5 is absent rather than shipped broken, HTML is decoded without ever touching the DOM, and invalid SQL is reported rather than reshaped into something that merely looks plausible.

That last point matters more than it sounds. These tools are useful precisely on the data you should not paste into a random website: a token from a production log, a payload from a customer bug report, a config file with internal hostnames in it. Nothing you paste is uploaded, and the page is locked down so that it could not upload it.