The only reason I was using the other browser was because of this awesome Add-ons and sadly it wasn't available on Firefox, but now I can finally use Firefox as my main browser and get to use Checker Plus for Gmail \o/ WebExtensions FTW! I love how I can do everything in one place and get notified whenever I received an email and the best part is having a unified inbox at glance! 5 stars is not enough TBH. Thanks!