Add and switch multiple Gmail accounts in basic HTML view
You can add additional user account by simply editing the URL in address bar by incrementing the number next to u/, say for example, when I am logged in to my primary account, the Gmail URL in the address bar will look like
To add and additional accout I am going to change the user number 0 to 1 and hit enter, now Gmail will prompt to enter user name and password for the next account.
Once you have added all your account by incrementing the number, you can switch between accounts by editing the user number in the URL, say for example, If I have added four accounts, the URLs will look like
Incrementing the number to 4 will add another account