Knock vs. Courier

Knock is infrastructure for sending product and customer messaging. Ship cross-channel product notifications and lifecycle messaging that drives engagement, growth, and retention. Knock has everything you need to power notifications for your product, including: - A powerful workflow engine to automate and manage your entire cross-channel motion, from in-product messaging to email and push notifications. - Branded, in-product messaging components, including embeddable inboxes, feeds, and lifecycle messages. - Broadcasts make it easy to send effective, one-time messages to custom audiences.

Courier is notification infrastructure for customer messaging, built for humans and AI agents. It sits between your app and every channel you send on: email, SMS, push, in-app inbox, chat, and webhooks. You send one request, and Courier works out where it goes, what it looks like, and whether the user wanted it at all. Teams use it for the messages a product has to send: onboarding, alerts, receipts, reminders, and account notices. You keep the providers you already pay for. Courier is the layer above them.