Knock

What is Knock?

Knock is customer engagement infrastructure that coordinates cross-channel messaging—email, in-app, push, SMS, and chat—for product, marketing, and transactional use cases. Knock differentiates itself by letting teams build lifecycle and transactional messaging workflows from a prompt through AI agents, the Knock MCP server, or the Knock CLI, then scale those workflows to large customer bases.

Key Features

• Cross-channel orchestration: Knock coordinates in-app and out-of-app flows so messages reach the right users at the right moments, with dynamic, on-brand delivery across email, in-app feed, in-app guides, SMS, push, and chat apps.
• Workflows: Trigger-based automations send messages across any channel. The workflow builder supports steps including Agent, Delay, Batch, Fetch, Branch, Experiment, Throttle, Wait for event, and data updates for users, companies, audiences, and objects.
• Agent steps inside workflows: An Agent step can call a model such as Claude Sonnet 5 with a prompt and write the result into a response property (for example, a personalized welcome line), which later steps reference via data.personalize_welcome_email. Agent configuration includes model selection, prompt, web search, response properties, and a halt-on-error option.
• Broadcasts: One-time messages sent to any audience across any channel.
• In-app guides: Banners, modals, cards, and tooltips built with the team's own components.
• Templates: Dynamic, on-brand templates and reusable content blocks organized as layouts, partials, and brand assets.
• Agent and developer tooling: Starter prompts for onboarding, trial ending, win-back, NPS survey, feature launch, weekly digest, usage limit, mentions, failed payment, and migration use cases, usable from agents including Knock, Claude, ChatGPT, Cursor, Grok, and Slack, or through the Knock MCP server at https://mcp.knock.app/mcp and the CLI installed with npm install -g @knocklabs/cli.
• Data activation: Sync warehouse data, identify users, and build audiences to target messaging.

Use Cases

• New user onboarding: A workflow triggers on new-user-signup, uses an Agent step to write a personalized welcome line, sends a welcome email on day 0, shows an in-app guide on first login, and after a 3-day delay branches on whether the user created a project—sending a tips email to those who have not and an in-app feed message to everyone else.
• Lifecycle messaging: Teams build flows for trial ending, win-back, feature launches, weekly digests, usage limits, and NPS surveys from starter prompts.
• Transactional messaging: Product and marketing teams send transactional notifications alongside lifecycle campaigns from the same infrastructure.
• Broadcasts and announcements: One-time messages are sent to a defined audience across any supported channel.
• In-product guidance: Banners, modals, cards, and tooltips deliver in-app guides using a team's own components.

Who It Is For

Knock is built for product, marketing, and engineering teams that need to run lifecycle and transactional messaging across multiple channels without stitching together separate systems. It suits teams that want to activate warehouse data, define audiences, and ship cross-channel workflows—including AI-assisted workflow creation through agents, the MCP server, or the CLI—while keeping messages on-brand through reusable templates and brand styles.

Pricing

The source material does not state Knock's pricing model, free tier, or trial terms. Pricing details should be confirmed directly with Knock.

Frequently Asked Questions

What is Knock used for?

Knock is used to orchestrate customer engagement messaging across email, in-app, push, SMS, and chat. Teams use Knock to build lifecycle and transactional workflows, send broadcasts, and deliver in-app guides from a single engagement infrastructure.

Which channels does Knock support?

Knock supports email, in-app feed, in-app guides, SMS, push, and chat apps. Workflows and broadcasts can send messages across any of these channels.

Can AI agents build Knock workflows?

Yes. Knock provides starter prompts for common use cases that work with agents including Knock, Claude, ChatGPT, Cursor, Grok, and Slack. Agents connect through the Knock MCP server at https://mcp.knock.app/mcp or the Knock CLI, installed with npm install -g @knocklabs/cli.

What workflow steps does Knock offer?

Knock workflows support Agent, Delay, Batch, Fetch, Branch, Experiment, Throttle, Wait for event, and data update steps for users, companies, audiences, and objects. These steps let teams personalize messages, branch on user behavior, and coordinate timing across channels.

Who should use Knock?

Knock is intended for product, marketing, and engineering teams running lifecycle and transactional messaging at scale. It fits teams that want to sync warehouse data, build audiences, and ship cross-channel workflows without maintaining separate messaging systems for each channel.