Knock

Knock is a product and customer messaging infrastructure. You can use Knock to power all of your product's messaging needs, including transactional messaging, lifecycle marketing, one-time announcements, and in-product messaging, without the effort of building and maintaining your own in-house messaging system. Knock is made with engineering, product, growth, and operations teams in mind. It's easy for developers to implement, and simple for less-technical users to maintain in our dashboard.