Reactions Sounds
A reaction soundboard for the half second after something happens, covering mock outrage, genuine shock, flat disappointment, smug agreement and applause. Play any reaction sound instantly, download it as a free MP3, or add it to Discord.

A reaction soundboard exists for the half second after something happens. Not the joke itself, the response to it. That's a narrow job and it explains almost everything about how these clips are built.
The Half Second After
Reaction audio has to arrive fast or not at all. If you're still choosing a clip when the moment passes, the clip has failed no matter how good it is, so everything here is optimised for instant recall rather than variety. Most people end up using four or five sounds and ignoring the rest. That isn't laziness, it's the format working correctly.
The good ones also read from a single hearing. A reaction that needs a beat of thought is a reaction that landed late.
Where They Actually Go
Voice chat, overwhelmingly. Reaction sounds are the closest audio equivalent to an emoji and get used the same way, as cheap punctuation on someone else's statement. In edits they play a different part, standing in for a cutaway to a face. Both uses want the same thing from a clip, which is an unmistakable emotional register in under two seconds. The sounds of memes here overlap heavily for that reason.
Reading the Room
Register matters more than the sound itself. Mock outrage, genuine shock, flat disappointment and smug agreement are four different responses, and reaching for the wrong one lands badly in a way that saying the wrong thing usually doesn't. A fahhh sound is theatrical shock. A goofy ahh sounds laugh is mockery. They are not substitutes for each other.
When to Not Press Anything
Reaction audio is the easiest thing on this site to overuse, because the opportunity comes up constantly. Every statement is technically reactable. People who use it well treat it as scarce, which keeps each one landing, and people who don't turn a conversation into a soundboard demo within about four minutes.
The rest of the sounds for a soundboard collection covers everything that isn't a response to something else.
Frequently Asked Questions
What makes a good reaction sound?
Speed and clarity. It has to be recallable instantly, since a reaction arriving after the moment has passed has already failed, and it has to read from a single hearing without anyone needing to work out what was meant.
How many reaction sounds do people actually use?
Usually four or five, regardless of how many are available. Reaction audio depends on instant recall, so a large collection ends up being a small working set plus a long tail nobody reaches for under pressure.
What is the difference between a reaction sound and a meme sound?
Mostly intent. A reaction responds to something someone else did, while a meme sound can be played for its own sake. In practice the two overlap constantly, and many clips work as either depending on when you press them.