Proton V4 web beta brings persistent single sign-on in huge step toward full integration

Proton 4.0 is now in beta

Today, we are marking a major milestone in our mission to expand privacy online with the launch of a new beta version of ProtonMail for web that includes crucial new features like Single Sign-On and persistent sessions (“remember me”). 

Today’s updates create the foundation of a fully integrated, private, and encrypted ecosystem covering all basic internet needs in a way that puts people first. These improvements are first coming to the web apps, but in the coming quarters they will also make it to mobile as we launch more apps and features that protect your digital privacy.

To achieve this, we have completely rebuilt our web apps using a new programming framework that will tie all our apps together. 

This beta update also includes new ProtonMail features, such as subfolders and multi-account access. And last but not least, we are deploying ProtonDrive in closed beta for Lifetime account users.

While some of these new features and beta products are available only to users with paid plans, anyone can take advantage of the convenience of Single Sign-On and persistent sessions. To access them, go to and sign in to your Proton account.

Access all Proton services with just one login

Single Sign-On and persistent sessions make it possible to quickly access ProtonMail, ProtonCalendar, ProtonDrive, and ProtonContacts and use them as a connected suite of tools. 

With Single Sign-On and persistent sessions, you don’t need to enter your username, password, and two-factor authentication every time you switch between apps or reopen your browser. You can simply sign in to your Proton account and start working in ProtonMail or ProtonCalendar while keeping your data secure.

Single Sign-On

Single Sign-On allows you to easily switch between ProtonMail, ProtonContacts, ProtonCalendar, and eventually ProtonDrive without having to sign in again. 

For the time being, ProtonVPN is being kept separate to give it stronger censorship resistance, as in certain countries ProtonVPN is used to access the rest of the Proton services. While Single Sign-On is currently available only for Proton web apps, we will eventually include it in our Android and iOS apps. 

Persistent sessions

The new beta will also include persistent sessions for our web apps. This allows you to sign in to Proton, close your browser, and return later to your ProtonMail, ProtonCalendar, and eventually ProtonDrive without signing in again. For security reasons, your session will have a limited lifetime of 60 days if you are inactive, meaning you might need to log in again if you do not use one of our web apps for several weeks. That’s why it is critical to always remember your password.

This feature is automatic. In practical terms, it means you will be able to go straight into your Proton account first thing in the morning without entering your login credentials at the start of every day.

Note: If you are using a shared device or are concerned about physical device compromise, you should log out of your Proton account to end your session. Closing the tab is no longer sufficient.

We completely rebuilt ProtonMail from the ground up

While you will quickly notice the new Single Sign-On feature, some of our most significant changes are invisible to users. We have written the new ProtonMail beta, as well as all our other new products, using the React programming framework. 

This is a crucial step that lays the foundation upon which we can build a fully integrated Proton suite in the future. Using React makes it much easier to incorporate ProtonMail with ProtonContacts, ProtonCalendar, and ProtonDrive, as well as any future Proton tools. Because of these changes, we will be able to design features that let you seamlessly move events from your inbox to your calendar or share files with your contacts.

Throughout this process, we have also improved our code to make it more maintainable. While this type of work does not generally result in noticeable user benefits, it is important to build a sound footing now in the early years of Proton, which will accelerate the delivery of updates and new features in the future and provide better performance for our users.


The new ProtonMail beta will also let you organize your messages into subfolders. You can add subfolders to any “parent” folder, and you will be able to make subfolders within subfolders (the maximum number of folder levels is three). Subfolders have been a popular request from ProtonMail users, and we are making them available to everyone, including free users. 

Multi-account access

The new ProtonMail beta will also include our multi-account feature, which allows you to be signed in to an unlimited number of accounts at the same time. This makes it easy to quickly manage multiple accounts, which is particularly useful for:

  • Business owners, who can quickly toggle through their different, role-based email accounts, responding to questions in support@, sales@, and admin@. 
  • Workers, who can easily switch between their personal and professional inboxes. 
  • Freelancers, who can create inboxes dedicated to important clients, allowing them to separate their workflows and stay organized.

ProtonDrive early access

After months of internal testing, we are ready to share ProtonDrive beta with our Lifetime account holders. If you have a Lifetime account, thank you for your exceptional support of our mission. You will shortly receive an email detailing how to start testing our encrypted cloud storage solution. 

We will then extend this early access beta to Visionary users before opening it up to all users with paid accounts. 

ProtonDrive will greatly expand the possibilities of the Proton suite and make it simple to privately store and share sensitive files. You can read more about how ProtonDrive will secure your files in the ProtonDrive security model

The next frontiers of freedom

One of the challenges of making privacy-focused tools is that they must be both secure and easy to use. The most secure email service in the world can’t protect any data if it is too complex for most people to use. The new ProtonMail beta is the first step toward a unified Proton that eliminates unnecessary steps and allows for the frictionless exchange of encrypted files and information between different Proton apps. 

Screenshot of ProtonDrive.

Thank you to all our users. Your support is what makes our work possible. As with all our betas, we rely on your feedback to help us improve Proton. During the beta, you can send us your comments and feedback on the new ProtonMail inside the web app

To report issues, click Help > Report bug.

And let us know what you think of the Single Sign-On, multi-account support, and subfolder features in the new ProtonMail beta on Twitter, Facebook, Reddit, Instagram, and Linkedin.

This is the next step toward building an internet where user privacy is the default. Thank you for helping us move online security, privacy, and freedom forward.

You can get a free secure email account from ProtonMail here.

We also provide a free VPN service to protect your privacy. ProtonMail and ProtonVPN are funded by community contributions. If you would like to support our development efforts, you can upgrade to a paid plan. Thank you for your support.

Feel free to share your feedback and questions with us via our official social media channels on Twitter and Reddit.

About the Author

Proton Team

Proton was founded by scientists who met at CERN and had the idea that an internet where privacy is the default is essential to preserving freedom. Our team of developers, engineers, and designers from all over the world is working to provide you with secure ways to be in control of your online data.