Knock

Knock is customer engagement infrastructure for developers: a single API that ships cross-channel notifications, in-app inboxes, lifecycle workflows, and recipient preferences without you having to build any of that yourself. We rate it 88/100 — for product teams that want to retire their tangle of SendGrid scripts, Twilio webhooks, and bespoke in-app feed code, Knock is the most polished managed option you can adopt today.

What is Knock?

Knock is a notifications platform founded in 2020 by Sam Seely (CEO) and Chris Bell (CTO) and headquartered in Brooklyn, New York. The company emerged from stealth with a public launch on March 22, 2022 and went on to raise an $18M total across two rounds — most recently a $12M Series A led by Craft Ventures in February 2024 (David Sacks took the board seat). Customers include Vercel, Mux, Linear, Modern Treasury, and hundreds of other product-led companies that have effectively outsourced their notifications stack.

The specific problem Knock solves is the one every growing SaaS hits around year two: notifications start as a single sendgrid.send() call and end up as a sprawling multi-channel system with email, SMS, push, in-app inbox, Slack, Teams, digesting, batching, throttling, internationalization, preference centers, and version control across staging and production environments. Knock collapses that into one API plus a dashboard the product team can actually edit.

Key Features of Knock

• Workflow engine: A visual editor where each notification is a workflow with steps for channels, batching windows, throttling, conditional logic, and delays. Triggered by a single API call from your backend.
• In-app inbox and feed components: Drop-in React, Vue, JavaScript, iOS, Android, React Native, and Flutter SDKs that render a notification bell, unread badge, and feed inside your product — fully themable, with read/seen/archive state managed for you.
• Multi-channel orchestration: Email (Resend, SendGrid, Postmark, AWS SES), SMS (Twilio, MessageBird, Plivo), push (APNs, FCM, Expo, OneSignal), in-app, Slack, Microsoft Teams, WhatsApp, and Discord — all configured per workflow.
• Knock Guides: Targeted in-app messages, banners, and announcements with audience targeting, version control, and analytics — Knock's answer to a hand-rolled product-update widget.
• Tenants and multi-tenant preferences: First-class support for B2B SaaS where notifications need to be configured per organization, not just per user — overrides cascade from tenant down to user.
• Preference center API: Per-recipient, per-channel, per-workflow opt-in/out flags, with a hosted preference page or your own UI driven by the API.
• Environments, version control, and Knock CLI: Promote workflow changes from development to staging to production via the CLI, validate templates in CI, and roll back any deployment.
• Observability: Per-message logs with full payload, channel response, timing, and delivery status — exportable to your warehouse via outbound webhooks or a Snowflake-style data export.

What Users Say About Knock

Sentiment is unusually warm for a paid SaaS. On G2 Knock holds a near-perfect rating, with reviewers consistently calling out the SDK quality, documentation, and the time saved by not maintaining a homegrown notification service. The most-quoted line on Reddit's r/webdev is some variation of "we ripped out three weeks of email + push + inbox glue code and replaced it with one Knock workflow." On Hacker News the original Show HN drew technical praise for the workflow primitives and the decision to charge per message rather than per recipient.

The recurring complaints are real and worth knowing. First, pricing scales fast: at 50,000 notifications a month you are paying $250, and at the volumes any consumer product hits, Enterprise pricing becomes the only option. Second, several reviewers note that the workflow editor still favors developers — non-technical product managers can edit templates, but creating new workflows usually means a developer commits a change. Third, a few teams have wished for richer A/B testing built in rather than via the data export.

Knock Pricing

Knock charges only for messages successfully sent — bounces and workflow runs that route to no channels are free. Three published tiers plus contact-sales Enterprise:

Plan	Price	Key Limits
Developer	$0	10,000 notifications/month, unlimited workflows, all channels, community support
Starter	$250/month	50,000 notifications/month, environments, in-app feed, email support
Growth	Custom	Higher volume tiers, advanced workflow features, priority support
Enterprise	Contact sales	SLA, SSO/SAML, HIPAA, audit logs, dedicated infrastructure, volume discounts

Knock Guides (in-app banners and product tours) is priced separately on a monthly active user model, with a 2,500 active-user limit on the Starter plan.

Who Should Use Knock?

Best for: B2B and B2C SaaS teams between 10 and 500 engineers who already have notifications scattered across services and want to consolidate, plus startups that need an in-app inbox shipped this sprint without writing a websocket layer. The multi-tenant primitives make Knock especially strong for B2B products with org-level admin controls.

Not ideal for: Solo founders sending under 1,000 messages a month (Resend's API plus a homemade feed is cheaper); marketing-led teams who need rich campaign analytics and A/B testing as the headline feature (Customer.io or Braze fits better); and teams that have a hard requirement to self-host (look at the open source Novu instead).

Pros and Cons

Pros:

• Best-in-class developer experience: TypeScript SDKs, a real CLI, environments, and inline schema validation in the dashboard.
• Drop-in inbox component that works in React, React Native, iOS, Android, Vue, and Flutter — no websocket plumbing required.
• Workflow engine handles batching, throttling, and digests cleanly — features that take months to get right in-house.
• HIPAA-eligible on Enterprise, with SOC 2 Type II — usable in regulated verticals.
• Charges only for successfully sent messages, not workflow triggers or bounces — predictable billing.

Cons:

• $250/month minimum on the first paid tier prices out very small teams once they exceed 10k notifications.
• Workflow creation is still developer-led; non-technical edits are mostly limited to templates.
• Not self-hostable — vendor lock-in is real, especially given how deeply notifications integrate with your product.
• A/B testing exists but is less first-class than dedicated marketing platforms.

Alternatives to Knock

The closest direct competitors are Courier, which leans more designer-friendly with a stronger template builder, and SuprSend, which competes on price and has a generous free tier. Novu is the open-source option — self-hostable and code-first via @novu/framework, but you carry the operational burden. For pure in-app feed-only needs, Liveblocks Notifications is worth a look. None of these match Knock's combination of SDK breadth and multi-tenant primitives, but each wins on a specific axis.

Verdict: Is Knock Worth It?

For any product team that has scaled past the "single email service plus a custom feed" stage, Knock is worth the price. The 88/100 reflects how complete and developer-friendly the platform is — the points it loses are for the steep first paid tier and the (deliberate) lack of a self-host option. If you are about to estimate "two engineers for a quarter to build proper notifications," buy Knock instead and ship it in a week.

Frequently Asked Questions

Is Knock free?

Knock has a free Developer plan with up to 10,000 notifications per month, all channels, and unlimited workflows. Paid plans start at $250/month for the Starter tier (50,000 notifications), with custom pricing on Growth and Enterprise.

What channels does Knock support?

Email (Resend, SendGrid, Postmark, AWS SES), SMS (Twilio, MessageBird, Plivo), push (APNs, FCM, Expo, OneSignal), in-app inbox, Slack, Microsoft Teams, WhatsApp, and Discord — all orchestrated from a single workflow.

How does Knock compare to Novu?

Knock is a fully managed SaaS with a richer SDK suite (especially the in-app inbox) and stronger multi-tenant primitives. Novu is open source and self-hostable, with code-first workflow definitions, which is preferable if you need data residency control or want to avoid vendor lock-in.

Is Knock open source?

The Knock platform is closed source, but Knock maintains numerous open-source SDKs and example apps under the knocklabs GitHub organization, including SDKs for JavaScript, React, React Native, Flutter, and a CLI.

Is Knock HIPAA compliant?

Yes. Knock supports HIPAA on the Enterprise plan and holds SOC 2 Type II certification, making it usable for healthcare and other regulated industries.

Does Knock charge for failed messages?

No. Knock only counts successfully sent messages toward your monthly quota. Bounces, errors, and workflow runs that route to no channels are not billable.