Debloat Slack is a small open-source injector that launches the native Mac Slack app with a debugging hook and pushes your own CSS and JS into every window, re-applying within a second whenever you save a change. It ships a config of toggles for the usual irritations — the Slackbot DM, the huddle button, the AI upsell banners — and leaves a hatch for hand-written rules for anything else. It’s a power-user fix (macOS, Node 22+, Slack already installed), but it’s the rare one that reaches into a native app you otherwise can’t theme at all.