> ## Documentation Index
> Fetch the complete documentation index at: https://www.courier.com/docs/llms.txt
> Use this file to discover all available pages before exploring further.

# What Is Courier?

> Courier is a unified notification API: one call delivers across email, SMS, push, chat, and in-app with routing, retries, and preference enforcement.

## Why teams use Courier

Without a unified layer, teams manage separate SDKs and provider contracts per channel, build custom retry and failover logic, and have no shared preference or delivery-tracking system. Every new channel multiplies integration work.

Courier replaces that with a unified delivery pipeline and a shared set of controls.

### Built for developers

Integrate once and stay out of the way. Courier handles channel logic so your code doesn't have to.

**[Send API](/docs/platform/sending/sending-overview)** ✉️ — deliver across every channel from a single message model.

**[Multi-channel routing](/docs/platform/sending/choosing-your-sending-strategy)** 🔀 — define fallback chains or parallel fanout per message; Courier abstracts provider differences.

**[Reliability primitives](/docs/platform/sending/delivery-pipeline-resilience)** 🛡️ — automatic retries, provider failover, and idempotency keys prevent duplicates and dropped messages.

**[Agent-native tooling](/docs/tools/ai-onboarding)** 🤖 — CLI, MCP server, and machine-readable docs let coding agents discover and call every API from their workflow.

### Built for your whole team

After the initial setup, non-engineers can manage notification content and policy without touching code.

**[Template Designer](/docs/platform/content/content-overview)** 🎨 — a visual editor for building branded notifications with drag-and-drop blocks.

**[Hosted Preferences](/docs/platform/preferences/preferences-overview)** 🔔 — a drop-in preference center where users control their channels and topics; Courier enforces opt-outs at send time.

**[Tenant scoping](/docs/platform/tenants/tenants-overview)** 🏢 — isolate branding, preferences, and routing per customer account for B2B scenarios.

**[Journeys](/docs/platform/journeys/journeys-overview)** ⚡ — orchestrate multi-step sequences with triggers, delays, and conditions for digests, reminders, and onboarding flows.

## Get Started

<CardGroup cols={2}>
  <Card title="Quickstart" icon="bolt" href="/docs/getting-started/quickstart">
    Send your first notification with cURL, CLI, or SDKs.
  </Card>

  <Card title="How Sending Works" icon="paper-plane" href="/docs/platform/sending/sending-overview">
    Learn routing behavior, channel strategy, and delivery pipeline details.
  </Card>

  <Card title="Build with AI" icon="brain" href="/docs/tools/ai-onboarding">
    Install Courier CLI, MCP, and skills for agent-assisted development.
  </Card>

  <Card title="Agent Quickstart" icon="microchip-ai" href="/docs/tools/agent-quickstart">
    A self-contained guide for AI coding agents with patterns, guardrails, and API reference.
  </Card>
</CardGroup>