
After two decades of engineering teams rebuilding the same unglamorous machinery, Troy Goode made notifications his full-time problem. Courier grew from that stubborn irritation into a venture-backed layer for software-to-human communication.
Knock is a New York-based notification and customer-engagement infrastructure company that gives developers a single API and dashboard to design, manage, and deliver messages across in-app, email, SMS, push, and chat channels. Founded in 2021 by former Frame.io leaders Sam Seely and Chris Bell, Knock lets product and engineering teams ship cross-channel notification workflows without building and maintaining an in-house system, and now powers messaging for companies like Vercel, Webflow, Amplitude, and Clay.
Courier is a San Francisco notification infrastructure platform that lets developers add multi-channel messaging - email, SMS, push, in-app, Slack and more - to their apps through a single API and a drag-and-drop designer. Often described as 'Stripe for notifications,' it routes messages intelligently across channels so engineering teams stop rebuilding notification systems from scratch. Founded in 2019 (YC S19), Courier raised a $35M Series B led by GV in 2022 and powers notifications for companies like New Relic, LaunchDarkly, Lattice, Vanta and Contentful.