Fully open-source: both SimpleLogin server and client code (browser extension, JS library, mobile apps) are open-source so anyone can freely inspect and improve the code.

Here are some differences between SimpleLogin and other email forwarding/alias services: SimpleLogin is the most advanced email alias solution and is in active development. You can read more about the pros and cons of using the + trick on What makes email alias a better alternative to email plus sign (+) SimpleLogin aliases don't have any of these downsides. By removing the + part, advertisers can link these + addresses together to have your browsing history. You could check whether your email is leaked using website like have i been pwned If your + address appears in the data breach, your real address is probably also in the hands of spammers.

Using + trick doesn't protect your privacy: one can easily remove the + part to have your real email. The + trick is well-known and some websites don't allow sign-ups with email addresses that contain +.

You cannot reply from the + address: your real email will appear as the sender. Says your email is you can quickly create another address like for Facebook, for Groupon, etc. Email subaddressing, also known as the plus (+) trick, popularized by Gmail and supported by some email services, allows you to create new email addresses by appending '+' to your current email address.

Protonmail sign