Some keyboard switches are louder than others, and sometimes that' son purpose. A clicky switch includes mechanisms that make noise to reinforce the feel, but even non-clicky switches can make a lot of racket as you're tapping away.
There are several remedies to keyboard noise, the most common being o-rings. These are easy to add to an existing keyboard, but some switches have built-in silencing. As long as you know you're going to want a quieter keyboard, you can use these instead of a standard switch. One of the newest silent switch options is the Zilent, which is a modification of the popular Zealio switch from Zeal PC.
Like Zealios, Zilents are based on a Cherry-style design from Gateron. The housings are fully transparent, making them compatible with per-switch RGB lighting as well as standard in-switch LEDs. You can tell Zilents from the very similar Zealios by the stem color. Whereas Zealios use various shades of purple to indicate different weights, Zilents use blue hues.
Zilents are tactile switches, and they're available in the same weights as Zealios—62g, 65g, 67g, and 78g. Those are bottom-out weights, so the lightest Zilents are similar in weight to a Cherry Brown switch, and the heaviest is a bit lighter than a Cherry Clear. The tactile bump, however, is more pronounced than most other switches (just like Zealios).
This is probably all sounding somewhat similar to Zealios so far, but the Zilent stems are designed with sound in mind. Zilent switches are superior to o-rings in two ways: they're quieter, and they feel nicer. An o-ring goes on the stem insert on the underside of your keycap. This reduces the noise from bottom-out, but the switch tends to feel "mushy." O-rings can't do anything about the sound of the stem returning and hitting the housing, either. Zilent stems dampen both parts of the press.
As you can see in the images above and below, there are small white bumpers on the side rails of Zilent stems. Those are the pieces that contact the housing as you press and release a switch. In a regular switch, they're just plastic that makes a "clacking" sound. In Zilents, the bumpers reduce the bottom-out and return sound. It's like having an o-ring inside your switches.
Zilent switches are available only from ZealPC, where you can order any of the four weights immediately. They're currently on sale for $0.90 per switch, down from $1.20 each. For a small 60% board, you're looking at around $55-60 in switches. They're a bit more expensive than other switches, but these are some of the coolest switches I've ever tried—I'm planning to use them in a future keyboard build.