head to head
Knock vs Courier
Code-first workflow engine versus visual-journey notification platform.
What matters for teams building autonomous agents
An agent stack treats email as a two-way primitive. Inbound has to arrive as structured JSON a tool call can consume, sends have to be safe to retry when a model loop repeats itself, and every action needs an audit trail. A provider without inbound parsing only solves half the problem.
| Priority | Knock | Courier |
|---|---|---|
| Inbound parsing | No | No |
| Idempotency keys | Yes | No |
| Webhooks | Yes | Yes |
| Operating since | 2021 | 2019 |
| Event stream | Yes | Yes |
| Best published rate per 1,000 | Tiers not published in comparable form | Tiers not published in comparable form |
| Batch sending | Yes | Yes |
| SDKs | node, python, go, ruby, php, elixir, java, dotnet | node, python, go, ruby, php, java |
| Multi-tenant | Yes | Yes |
For an agent that reads and writes email running inbound parsing into tool calls and model-generated sends that must not duplicate, Knock takes idempotency keys and SDK breadth, while Courier takes operating track record. That ordering reflects this audience. Weigh the same table differently and the answer changes.
Side by side
| Feature | Knock | Courier |
|---|---|---|
| Webhooks | Yes | Yes |
| SDKs | node, python, go, ruby, php, elixir, java, dotnet | node, python, go, ruby, php, java |
| Multi-tenant | Yes | Yes |
| Tagline | Notification infrastructure with workflow engine. | Notification infrastructure with visual journeys. |
| Free tier | 10,000 notifications/mo | 10,000 sends/mo |
| Starts at | $249/mo (Starter) | $95/mo (Business) |
| Pricing model | volume | volume |
| API | Yes | Yes |
| SMTP | No | No |
| Templates | rich | rich |
| React Email | Yes | No |
| Inbound | No | No |
| Idempotency | Yes | No |
| Dedicated IP | No | No |
| Deliverability | Inherits the deliverability of the provider you BYO (Postmark, SendGrid, Resend). | Inherits providers you connect. |
| DX score | 9/10 | 8/10 |
| Best for | Teams that need multi-channel product notifications with preferences. | Teams that need both product notifications and marketing-style journeys. |
Knock
pros
- ›Strong workflow engine
- ›In-app feed component
- ›Deep SDK coverage
- ›Idempotency keys
cons
- ›Pricier than running your own; entry plan is steep
- ›Bring your own delivery provider
Courier
pros
- ›Visual journey editor
- ›Native Slack/Teams routing
- ›Drop-in inbox component
cons
- ›Less code-first than Knock
- ›Pricing climbs with volume