While I'm planning to eventually self-host anonaddy[1] or SimpleLogin[2], I'm currently happy with Fastmail.com's masked email feature[3].
90% of my own usage consists of entering `masked_fastmail website.com`, which will get the alias for website.com or create one if it doesn't exist. The alias is automatically copied to clipboard. There's a GIF of how this works in the project README together with some more examples.
The CLI tool is written in Go and is very simple. I've used it myself for almost 1 year now. I made some upgrades yesterday and wanted to share it here in case it's useful for someone else :)
[1] https://github.com/anonaddy/anonaddy