Utilities that never see a server
Developer utilities have an awkward habit of being the least private tools on the internet. You paste an API response into a JSON formatter, or a token into a base64 decoder, and that text is posted to somebody's backend, logged, and possibly retained. For anything carrying a credential, a customer record or an internal identifier, that is a genuine problem.
None of the tools on this page work that way. They are plain JavaScript running in your tab: the text you paste stays in the page, the result is computed locally, and closing the tab is the end of it. There is no request to inspect, because there is no request. That also makes them instant — no round trip, no spinner, output as you type.
The collection covers the small jobs that come up constantly during a working day: prettifying and validating JSON before it goes into a ticket, converting between camelCase and snake_case, generating a SHA-256 to verify a download, diffing two blocks of config, counting words against a limit, or turning a Unix timestamp into something a human can read.