Why it exists

Your email address is the de-facto primary key of your online life: it links accounts across companies, and once it leaks it lands on every spam and phishing list. Disposable-inbox sites only half-solve this, because replies and password resets can never reach a throwaway. SimpleLogin makes the alias a permanent, two-way identity: senders see only the alias, mail arrives in your normal inbox, and you reply straight from it while the alias mask stays on. Crucially, the whole system is open source, so the service can also be run on your own server.

Main features

• Aliases everywhere — create aliases on the fly via the browser extension, mobile apps or a wildcard catch-all on your subdomain (anything@yourusername.si.onl-style); the first incoming email auto-creates the alias.
• Two-way anonymous replies — hit reply on a forwarded email and the answer goes out from the alias; compose directly from the web UI or apps as well.
• Kill switch — deactivate an alias and further mail is silently discarded; delete it to bounce senders — ideal when an address starts attracting spam.
• Multiple mailboxes & subdomains — forward aliases to several destinations, use shared public domains so your username never appears, or bring your own domain.
• PGP encryption of forwarded mail — outbound forwarding can sign; mail can be encrypted to your key before it leaves SimpleLogin.
• Self-hostable — the server, web apps and mobile apps are all AGPL-3.0; Docker deployment is documented.
• 1,000,000+ users and strong standing in the privacy community (recommended by Techlore, Michael Bazzell, Naomi Brockwell).

Who it's for

• Anyone signing up to newsletters, shops and services who wants each relationship severable.
• People with a leaky history: point the aliases at a fresh inbox and abandon the old one cleanly.
• Privacy-minded self-hosters who want a Swiss-hosted or home-run alias server.

How it compares

• addy.io — the other major open-source aliaser; comparable feature set (both support wildcard aliases, your own domain, PGP), so the choice is mostly ecosystem and price.
• Firefox Relay / Apple Hide My Email — slick but closed; Relay is tied to Mozilla, Hide My Email to Apple devices.
• + plus-addressing (user+site@gmail.com) — free, but the base address still leaks, can't be turned off per-site, and many forms reject plus signs.
• Proton Pass and similar password managers bundle aliasing, but SimpleLogin's is the reference implementation.

Notes

• The free tier allows 10 active aliases; paid SimpleLogin Premium raises limits and unlocks custom domains — and ships included with every Proton Unlimited plan.
• Owned by Proton since 2022, with infrastructure in Switzerland; the company's stated funding model is subscriptions, not data.
• The UIs are plain and quick; the mobile apps even work with self-hosted instances.
• Aliases are forwarded, not stored, so SimpleLogin is deliberately useless as a mail archive.

Useful links

• Official site: https://simplelogin.io/
• Source code: https://github.com/simple-login/app
• Documentation: https://simplelogin.io/docs/
• Comparison with plus-trick, Firefox Relay and Hide My Email: https://simplelogin.io/blog/comparison/