Developer tools, all in one cave.
Fast, free, and private. Every tool runs in your browser — no sign-up, no tracking, and nothing you paste ever leaves your device.
There is no server to send it to. Here's how to check that in thirty seconds →
We work out what it is and take you to the right tool. Nothing is sent anywhere.
Your tools
Nothing leaves the cave.
Tools compute locally, so there is nothing to upload and nothing to log. How you can check
Works offline
Install it, and the whole cave comes with you — which is only possible because the work was never happening elsewhere.
No sign-up, ever
Every tool is free and instantly usable. No account, no email, no quota.
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Why another developer tools site?
Because the existing ones are interchangeable. You search for a JWT decoder, click a result, paste your token, get your answer, and forget where you were — and next week you search again. The tools work, but nothing about them earns a second visit, and it is never obvious what else the site can do.
DevToolsCave is built on the opposite assumption: that the catalog is the product. Every tool links to related tools, a command palette (Ctrl + K) reaches any of them from any page, and the box at the top of this page will identify what you paste and send you to the right tool without you having to know its name.
Everything runs in your browser
These tools are JavaScript that executes on your device. Nothing you type or paste is sent anywhere, because there is no backend to send it to — a distinction that matters most for exactly the values developers paste into utilities like these: access tokens, API keys, internal identifiers, rows copied out of a production log.
You do not have to take that on trust. Open your browser's developer tools, watch the Network tab, and use any tool here; no request leaves the page. The same property is what lets the site work with no connection at all once installed.
Correctness before features
A utility that is quietly wrong on unusual input is worse than no utility, because you cannot tell which answers to trust. Every tool's logic is unit-tested against its awkward cases — empty input, malformed input, multi-byte characters, boundary values — before its interface is built, and invalid input clears the result rather than leaving a stale one sitting next to it looking correct.
That principle costs features, deliberately. The
time zone converter will not recommend a meeting slot,
because it cannot know anyone's working hours — it shows every city at the instant you pick
and lets you decide. The
JWT decoder reads a token's claims but says plainly that
it cannot verify the signature without the key. The
table calculator has no formula bar, because almost
nobody typing =SUM wants a formula — they want the number once. Being clear
about the edge of what a tool knows is worth more than a confident guess.