Knock is developer-first messaging infrastructure that provides APIs and SDKs for engineering teams to build custom notification systems. Klaviyo is primarily a marketing automation platform designed for e-commerce and marketing teams to create campaigns and flows.

Knock focuses on transactional product notifications and in-app messaging across multiple channels, while Klaviyo specializes in marketing automation and customer segmentation for e-commerce.

While Klaviyo can send transactional messages, it's primarily built for marketing campaigns and flows. Developers often find Klaviyo's workflow builder limiting for complex notification logic, whereas Knock provides programmatic control through APIs and code-based workflows designed specifically for transactional product and customer messaging use cases.

Knock excels at product and customer messaging use cases like user onboarding flows, activity notifications, system alerts, and other product-driven communications.

However, features like Broadcasts and Guides allow engineering, product, and growth teams to work collaboratively to send relevant lifecycle messaging and one-off promotional emails, just like Klaviyo.

Unlike Klaviyo, which prioritizes marketing workflows, Knock is purpose-built for developers, so initial setup requires some technical involvement.

From there, non-technical users can easily create messaging workflows, manage notification templates, edit and send one-time messages, ship in-app messaging, and view analytics without any developer involvement.

Klaviyo offers email marketing analytics for campaign performance and customer segmentation. Knock also provides extensive engagement analytics across channels, plus end-to-end observability for delivery tracking, message debugging, and API logs.

Knock is built as infrastructure to handle billions of notifications with guaranteed delivery and idempotency. While Klaviyo can handle large volumes, it's optimized for marketing campaigns rather than real-time, event-driven notifications at scale.

Klaviyo supports email, SMS, mobile push, WhatsApp, and other marketing channels. Knock supports email, push, SMS, in-app notifications, and chat apps like Slack and Microsoft Teams.

Knock allows integration flexibility with 25+ messaging providers, so AWS-native companies can save costs by using Amazon SES for transactional emails or use Twilio's infrastructure to reach 180+ countries via SMS.

Unlike Klaviyo, Knock also provides native in-app messaging components and integrations with chat apps like Slack and Microsoft Teams, plus webhooks for custom channels.

Yes, many companies use both platforms. It's common to see engineering teams using Knock to handle transactional messaging (alerts, updates, collaboration messages) while marketing teams use Klaviyo to manage marketing campaigns and flows.

However, this separation can lead to inconsistent messaging over time, and using two systems ends up costing more than just using Knock to handle all product and customer messaging.

Knock typically offers more cost-effective pricing for engineering teams building notification systems. While Klaviyo uses tiered pricing based on contacts and features, Knock provides transparent usage-based pricing starting at $0 for the first 10,000 notifications, making it accessible for startups and growing companies, with volume discounts for larger enterprise organizations.

All plans include unlimited data ingestion and unlimited channels with no onboarding or service fees, and overages are only incurred by volume of sent messages.

Both platforms offer enterprise compliance features. Knock provides SOC 2 Type 2 certification and supports GDPR/CCPA requirements. Klaviyo offers similar compliance but typically requires enterprise contracts.

Knock's infrastructure approach gives engineering teams more control over data handling.

Knock is designed for rapid implementation by developers, with most teams shipping notifications within hours using pre-built components. Klaviyo typically requires weeks of migration, configuration, and training for marketing teams.

If your engineering team needs to ship quickly, Knock's developer experience provides faster time-to-value.

Most engineering teams migrate from Klaviyo to Knock within 2-4 weeks, depending on notification complexity. Knock's responsive support team help accelerate the process.

The investment pays off quickly through improved developer productivity and reduced maintenance.