Being online means this equalizer is available the moment you open the page — no installer to download, no permissions to grant.
Open the same page on a desktop at home or a laptop at work and you get the identical four-band layout and controls. Nothing is tied to a specific operating system, so there is no separate version to track or update.
The page itself needs to load once over the internet, but from that point on, all audio decoding and filtering happens locally using your browser's Web Audio API — your connection speed has no effect on sound quality or processing speed.