Volume Booster от Hasan Sangrento

Volume Booster is a lightweight utility that boosts the audio volume of web pages beyond the browser's default limit, up to 600%. It performs this function entirely locally within your browser, processing audio in real time without ever accessing, recording, or transmitting the content you listen to.

The only permission the extension requests is storage, which is used exclusively to save your preferred volume level so it persists across sessions — this data never leaves your device. Volume Booster does not collect personal information, browsing history, analytics, or any other user data, and does not communicate with external servers.