The short version

Klack is a paid app with a polished, minimal interface and a curated set of switch sounds. Mechro is free, has a larger soundpack library, and lets you control keyboard and mouse volume separately. If you want a clean paid experience with a small, high-quality selection, Klack is a good pick. If you want more variety, mouse sounds, and no cost, Mechro is the better fit.

Pricing

Klack is a paid app. You buy it once and use it. That's fair and it supports the developer, and for a lot of people the one-time cost is worth it.

Mechro is free. No ads, no premium tier, no upsell. It's funded by being a project the developer actually wants to build, not by a business model.

Soundpack library

Klack ships with a smaller, tightly curated set of switches. Every pack is high quality and there's no filler.

Mechro's library is larger and still growing. It covers the popular Cherry MX line, Gateron switches, Holy Panda, Topre, and several themed packs like typewriter, retro, ASMR, and gaming. If variety matters to you, Mechro wins here.

Mouse sounds

Klack focuses on keyboard sounds. Mechro plays mouse click sounds too, with separate soundpacks for left click, right click, and scroll. If you want the full audio experience - keyboard and mouse together - Mechro is the only one of the two that delivers it out of the box.

Per-side volume

Mechro lets you set independent volumes for keyboard, mouse, and master output. Klack gives you one keyboard volume. If you like your keyboard quieter than your mouse clicks, or vice versa, that's a real difference.

Interface

Klack is genuinely well-designed. It's minimal, focused, and the visual language is clean. It feels like a piece of paid software should feel.

Mechro goes for a darker, more technical aesthetic with a larger feature surface. If you like minimal and don't mind paying for it, Klack wins on polish. If you want more options and don't mind a slightly busier UI, Mechro wins.

Platform support

Both apps target Windows. If you're on macOS or Linux, check the current state of both before committing - neither has guaranteed cross-platform support today.

Which one should you pick?

Pick Klack if: you want a polished paid app, you only care about keyboard sounds, and you prefer a small curated selection over a large one.

Pick Mechro if: you want a free option, you want mouse sounds too, you want per-side volume control, or you want the freedom to switch between a wide range of packs.

They're both good apps. The right choice depends on what you actually want out of a keyboard sound tool, not on which one is "better" in the abstract.