Knock

- Knock emphasizes workflow orchestration beyond simple send APIs and provides developer-oriented tooling. - Courier positions itself toward hybrid product and marketing messaging with a wider channel catalog; verify current integration lists when comparing. - Novu’s open-source/self-hosting model differentiates on control and cost flexibility but shifts operational responsibility to the customer. - Building internally remains an option for teams with unusual routing/eligibility requirements or mature platform engineering, but internal builds typically incur hidden maintenance and governance costs. - Market signals such as press coverage and review volume indicate category growth and adoption, but review platforms can contain selection bias; evaluate review recency and reviewer verification.