Single App, Multi Login - Proof of Concept

Google, Instagram, Twitter, and many other services allow users to login to multiple accounts and to switch between them without having to logout from one and login to another.

At BuildOn Technologies, I saw the need for a similar solution, so I have decided to create a Proof of Concept to assess how easy it can be done with Angular, and whether this is the right solution for us.

How is it done?

Google's approach is the oldest I have seen as I used it for many years. When you go to Gmail, you will notice the URL looks like this where N is the index of the account starting from 0. This allows the Frontend app to identify which account it should get data for from the server or localStorage and gives you the ability view different accounts in different tabs, where refreshing does not affect which account/page you are viewing.

Looking at Gmail's cookies, you will notice that the keys GMAIL_AT and COMPASS have their Path values correspond to /mail/u/N and I believe this is where each account's token is stored.

Twitter's approach is a bit different, you cannot use different accounts in different tabs, once you switch to a different account in one tab, the other tab switches the account right away, I believe they use the BroadcastChannel Web API to detect the switch, and then refresh the whole page. As for Instagram, I could not test their multi-login mechanism, but I would think it behaves in a similar way to Twitter.


My goal is to imitate Google's approach with some twists:

Tracking logins and workarounds:

As mentioned, Google forces you to logout of all accounts and that is due to the use of indexes they assign for each account, you cannot logout of account 3 (index 2) and still use account 4 (index 3). If we follow Google's approach, we would be giving up on the ability to logout from accounts independently. Unless we use random digits instead of in-order indexes.

We could also use query parameters instead to detect which account we are currently using, but we would still face the same logout issue, unless we use random digits instead of indexes. ?account=536

My preferred solution is to use a mix of localStorage and sessionStorage to keep track of the user in each tab. localStorage keeps track of all the accounts that are logged in, while sessionStorage can store which of these accounts we are using in the current session. This should allow using different account in different tabs, refreshing does not remove your session, but closing the tab does.

So, what happens if we visit a link in a fresh tab IF we are already logged into multiple accounts? Well, we can show the user a list of accounts, they can choose which to use. And this is a pro and a con:


This POC is done using Angular. To view the completed solution head over to

Let's walk through some files to explain what is going on: