I put my own "no-upload" tools on a network monitor. Here's what actually left the browser.

"Runs in your browser, nothing uploaded" is the easiest claim in web tooling to make -- and one of the easiest to fake. A tool can pretty-print your JSON locally and quietly POST it to a server for "analytics." The only way to know is to watch the network. So I did that to my own tools. I opened 15 of them across nine categories with the browser's...