About 99tools

Why the tools run in your browser

Most online utilities work by sending what you paste to a server, doing the job there, and sending the result back. That is convenient to build and it means the site operator can see everything that passes through: the API response with customer records in it, the token you were debugging, the contract you wanted to compare.

Every tool here does its work in the page, using ordinary browser JavaScript and, for a few heavier jobs, WebAssembly loaded on demand. Nothing you paste or drop into a tool is transmitted anywhere. You can verify that yourself: load a tool, switch off your network connection, and it keeps working.

What that costs, and what it buys

The constraint rules some things out. There is no server to remember your work between visits, so there are no saved documents and no accounts. Two jobs cannot be done in a browser at all — a DNS query, and reading the address your connection arrives from — so those are answered by this site’s own server and carry a badge saying so, which means the exception is never a surprise.

In return the tools are fast, because once the page has loaded there is no round trip; they are free to run at any scale, because your machine does the work; and the privacy claim is structural rather than a promise in a policy.

How the tools are written

Each tool separates its logic from its interface, and the logic is tested — more than three thousand tests across the collection. The text on each tool page describes what the implementation actually does, including its limits, rather than what a tool of that name is generally expected to do. Where a tool cannot do something, the page says so.

Who makes it

99tools is built and maintained by one developer, as an independent project. It has no investors, no ads at present, and no data to sell, which is a large part of why it can make the promises above.