How can a tool work without uploading my file?

Modern browsers can read, edit and export files entirely in JavaScript and WebAssembly, on your own machine. The file is opened from disk into memory, processed there, and saved back out. A server is never part of the loop, which is why these tools also work with your network disconnected once the page has loaded.

What exactly should I look for in the Network tab?

After loading a tool, clear the Network log, then use the tool on a file. You are looking for any request with your file as the payload, usually a POST or PUT with a large request body. You will not find one. The only requests are the page assets, fonts and, on the hub, ad scripts, none of which carry your file.

Do the ad scripts see my files?

No. Ads run on the hub pages and load their own scripts, but they have no access to the files you process on the tool subdomains, and the tools do not pass your data to them. The file stays in the tool page in your browser.

Is this true for every tool on the network?

The file tools (images, PDFs, developer utilities, color) all run in your browser with no upload. The calculators take numbers you type and compute locally too. If we ever add a tool that must use a server, we will say so on that tool, plainly.

Privacy

Privacy you can verify.

Every file site says it is private. Saying it is cheap. So here is a demo you can run right now, plus the exact steps to check us in your own browser. No trust required.

Hash a file, in your browser

Pick any file. It is read and fingerprinted on your device. Nothing is sent.

Choose a file It never leaves this page

Network uploads from this demo: 0 We are watching this page's fetch and XHR calls. The number stays at zero because the file is processed in memory.

Check us yourself in 30 seconds

The demo above is our word made testable. Here is how to confirm it on any tool in the network, using a panel that ships in every browser.

1
Open any tool, for example the image compressor.
2
Open your browser DevTools (F12 or right-click, Inspect) and select the Network tab.
3
Click the clear button to empty the request log, then use the tool on a file.
4
Watch the log. You will see asset and font requests, but nothing carrying your file.

Why this is possible

Browsers grew up. They can read a file from disk, run real processing on it with JavaScript and WebAssembly, and write the result back out, all without a server. That is the whole trick. The work that used to need an upload now happens on the same machine the file already lives on.

It is also why these tools keep working if you go offline after the page loads. There is no server waiting for your data, because your data was never going anywhere.

Frequently asked questions

How can a tool work without uploading my file?: Modern browsers can read, edit and export files entirely in JavaScript and WebAssembly, on your own machine. The file is opened from disk into memory, processed there, and saved back out. A server is never part of the loop, which is why these tools also work with your network disconnected once the page has loaded.
What exactly should I look for in the Network tab?: After loading a tool, clear the Network log, then use the tool on a file. You are looking for any request with your file as the payload, usually a POST or PUT with a large request body. You will not find one. The only requests are the page assets, fonts and, on the hub, ad scripts, none of which carry your file.
Do the ad scripts see my files?: No. Ads run on the hub pages and load their own scripts, but they have no access to the files you process on the tool subdomains, and the tools do not pass your data to them. The file stays in the tool page in your browser.
Is this true for every tool on the network?: The file tools (images, PDFs, developer utilities, color) all run in your browser with no upload. The calculators take numbers you type and compute locally too. If we ever add a tool that must use a server, we will say so on that tool, plainly.