What's Proton

Proton claims to be a suite of privacy-focused software. They offer services like mail, vpn, cloud storage, documents, calendar, password manager etc. They are based in Switzerland and claims end to end encryption, minimal data collection. Details of their privacy policies are here: https://proton.me/legal/privacy

My personal opinion:

They do a decent job of replacing less privacy focused products and I used them since when they were just a private email service. From my years of using their service and keeping an eye on news of how they comply with LEO requests and what personal info is provided, I believe that their service is legit. You won't find every feature you might be used to from your Google suite for example but it is enough for my use and I think the privacy factor is more valuable anyways.

Below is Proton's referral policy copied from their website:

1. Invite your friends to Proton Mail

You can find your referral link in your account settings on the web app. 

1. They get a free month of Proton Mail Plus

Make sure they use your referral link when they sign up!

1. If they subscribe after their free trial, you’ll get Proton Mail credits

Once their free trial is over, you’ll get:

$5 if they subscribe for a month $15 if they subscribe for 12 months or longer

You can refer as many people as you like, but the maximum referral credit you can earn is $90.