The short version: your audio never leaves your device, because there is nowhere for it to go.
Audio you open in Ducker is decoded and processed by your own browser, using the Web Audio API. It is never uploaded, never transmitted, and never seen by any server. There is no server: the site is a static page, and everything it does happens on the machine in front of you. Closing the tab discards it.
Ducker saves your current arrangement to your browser's own local storage so an accidental refresh does not lose your work. That data stays in your browser, is readable only by this site, and never leaves the device. You can clear it from inside the tool by choosing Start fresh when it offers to restore, or by clearing site data in your browser. Recorded microphone audio is held in memory for the session only and is not written to storage.
Recording asks your browser for microphone access, which you have to grant explicitly. The audio is kept in the page and used only to make the clip you recorded. It is not uploaded and not retained after you close the tab, unless you choose to save a project file, in which case it is written into the file you save, on your own machine.
There are no advertising trackers, no analytics tags, no cookies set by this site, and no third-party scripts other than a web font served by Google Fonts. The site is hosted on Netlify, which keeps standard server access logs of requests, as any web host does.
Ducker is made by M.J. Ricciardi. If something here is unclear or you have found a problem, get in touch and it will be looked at.