One app is way too loud on Mac — how to cap it

macOS has no per-app volume, so there's no native way to cap one loud app — turning down the system just quiets everything at once. To hold a single app at a ceiling, you either lower its own slider (if it has one) or install a per-app mixer that pins that app to a fixed lower level while your music, calls, and alerts stay exactly where they are.

You know the app. A game that peaks like a jet engine, a Discord voice channel that clips, a video with audio mastered twice as hot as your playlist. Everything else on your Mac sits at a sane level, and then this one app buries it. The instinct is to reach for the volume keys — but those move the master output, so you end up dragging your whole mix down to tame one offender, then dragging it back up the moment the offender goes quiet.

Why one app blasts over everything else

Two things stack up here. First, apps don't agree on a reference level. A music service targets a loudness standard; a game engine renders effects at whatever peak the sound designer chose; a screen recording or a random web video can be mastered anywhere. They all feed the same output, so identical "system volume" produces wildly different perceived loudness depending on which app is talking.

Second, macOS mixes every app through one master fader with no per-app normalization and no per-app cap. There is no Sound preference, no menu, no keyboard combo that says "never let this app exceed 40%." The operating system treats a hot game and a quiet podcast as equals routed to the same bus. That's the whole reason a Windows-style per-app control has to come from third-party software — the hooks simply aren't in the OS. If the reverse ever happens to you, where an app is too quiet even at full, the same missing layer is behind it; we cover that in why one app is too quiet even at full volume on Mac.

Option 1 — Turn down the app's own slider (free, if it has one)

The cheapest cap is the one built into the loud app. Games usually have a master and an effects slider in settings. Discord has per-user and output volume controls. Browsers and media players have their own level. Drop that slider and the app gets quieter without touching anything else.

The limits are real, though. Plenty of apps — system alerts, many utilities, some games that ignore their own setting mid-session — have no usable slider, or one that resets. And even when a slider exists, it's buried in a different place in every app, so "cap the loud one" becomes a hunt through preference panes every time a new app misbehaves. For a one-off it's fine. As a habit it's the exact friction that makes people go looking for a real mixer.

Option 2 — Pin the app with a per-app mixer (the real cap)

A per-app mixer sits at the audio layer macOS leaves empty and gives every running app its own level in one place. This is the only approach that works for apps without a slider of their own, and the only one that lets you set a ceiling once and have it stick. You pin the loud app at, say, 35% and leave it — everything else keeps running at full. Tools in this space include Background Music (free, open source), SoundSource by Rogue Amoeba (paid, deep), and Fader (paid, keyboard-first).

They all set a per-app level. Where they differ is how fast you reach the control and whether the app is still maintained — which matters a lot when the loud app changes from hour to hour.

A word on the free option, because "free" always sounds like the answer: Background Music is a genuinely useful open-source utility (GPLv2) that gives each app a volume slider in the menu bar and can even boost quiet apps above their max. The honest caveat is that it hasn't been updated as consistently for the newest macOS releases, and it installs a virtual audio device to do its work. If you want a zero-cost cap and don't mind that, it's a fair pick. If you want something that stays current and gets out of your way, a paid mixer is the trade.

Why reaching the cap fast is the whole game

Setting a cap once is easy in any of these. What you feel day to day is how long it takes to reach the control the next time an app surprises you. A menu-bar list means move to the menu bar, click the icon, find the row, drag the slider, dismiss. Five actions to tame one loud app — and you'll do it again in ten minutes when a different app spikes.

Fader's bet is that the fastest controller you own is already under your hands. You hit a toggle hotkey, the keyboard becomes a mixer — the Q/A/Z column is one app, W/S/X the next — and you ride a level down with letter keys without leaving what you're doing. When a game clips or a call gets shouty, you cap it in a keystroke instead of going mouse-hunting. Set the loud app's fader low, and it stays there across relaunches. That's the difference between a cap you set once and forget, and a cap you actually keep on top of.

Cap it without dragging the rest down

The core move is simple: leave the system volume alone, and only touch the loud app. That keeps your music, your call, and your notification sounds exactly where you like them while the offender comes down to meet them. If your real goal is broader — one app quieter than the others in general, not just a hard ceiling on a spiker — the same tool does it. We walk through the everyday version in how to lower one app's volume without lowering everything on Mac.

Bottom line

There's no native per-app cap on a Mac, and the volume keys can't give you one — they move the whole mix. For a single offender with its own slider, turning that down is free and fine. For anything without a slider, or for a cap you set once and reach in a keystroke every time an app spikes, a per-app mixer is the fix. If keeping the loud one pinned without ever breaking your flow is what you're after, that's exactly what Fader is built for.