Knock

knock.app/

Knock is messaging infrastructure that lets companies build and send product, marketing, and transactional notifications across email, SMS, push, chat, and in-app from one system instead of wiring up each channel separately. Its homepage leads with "Agentic customer engagement to grow faster," pitching itself at AI-agent-built workflows and offering direct integration with Cursor, Claude, and Codex alongside a CLI. It backs this with concrete operational figures — a 99.99% uptime number, "hundreds of millions" of messages sent monthly, and SDKs across eight-plus languages — plus a compliance list (HIPAA, SOC2, GDPR, CCPA) aimed at enterprise buyers. A customer quote on the page claims work that "used to take weeks now takes minutes."

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Knock | Customer engagement infrastructure

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Updated

Sep 22, 2026