addy.io has slowly become one my most favorite security & privacy services. It's easy to use, has a generous free plan, and it is open source. So far, the browser extension has not failed on me yet.

Очень хороший add‑on для приватности, удобно создавать псевдонимы электронной почты, подписывать (автоматически или вручную) и быстро находить их. Можно завести аккаунт на Hostux.App, где больше бесплатных возможностей, чем на официальном сервере.
Например, можно написать мне на e‑mail 📧 → f1795f5d-6a72-4f83-9a35-99428d4554d5@Hostux.App

It's my go-to email alias app. LOVE this! Dev responds to help question quickly!

Came to pin a note that it's highly recommended. I'm actually not sure why it's not spoken about more widely on the web, like with some other, similar purpose, services/platforms.
The initial figuring out might take a while, in terms of adjusting to layout, understanding what-where, then employing it. But it's worth it, as past that stage it does the job - and it's then so easy and quick!
Very user-friendly in that sense. Bonus that there's great support - if one needs to contact for help, my experience is quick response and being tended to!
So 5 stars fair & square!

first time rating something whatsoever. worth it.

Positive: Supports sidebar. Adheres to system theme by switching between light and dark. Negative: Requires API key generation rather than OAuth login.

Saves time. Has worked great in FireFox since my first use, now it been about 10 months and still works great. Easy to manage alias's.
Thanks.

The best option, with more features and it isn't geo-resticted, unlike Relay

A great extension for a great service. It is simple which is exactly what I need. Just plug it in and load your aliases. My only complain is that aliases take up to ~5 seconds to load.

Very handy dashboard of generated email aliases.

Free subscription even better than firefox relay's one