Courier

# Courier > Courier's developer documentation and API reference. ## Docs - [Developer Docs: Multichannel Notification API](https://www.courier.com/docs/welcome.md): Build notifications and lifecycle marketing from one API. Orchestrate journeys, manage user preferences, and reach users on email, SMS,… - [Quickstart](https://www.courier.com/docs/getting-started/quickstart.md): Send your first Courier notification with one API call using cURL, the CLI, or a server SDK. No dashboard setup required, plus a path f… - [How Sending Works](https://www.courier.com/docs/platform/sending/sending-overview.md): A single Courier API call handles rendering, routing, preferences, and delivery across email, SMS, push, inbox, and chat—from your app… - [Send a Message](https://www.courier.com/docs/platform/sending/send-message.md): Send notifications from your app across email, SMS, push, chat, and in-app Inbox with a single Send API request. - [Choose a Sending Strategy](https://www.courier.com/docs/platform/sending/choosing-your-sending-strategy.md): Courier offers three ways to send notifications, from a single API call to fully managed journeys. Start simple, add orchestration only… - [Responses & Error Codes](https://www.courier.com/docs/platform/sending/handling-responses-and-errors.md): Interpret Send API success and error responses, add production error handling, and track delivery status via the dashboard and webhooks. - [Delays & Delivery Windows](https://www.courier.com/docs/platform/sending/delay.md): Schedule message delivery with a duration delay, an exact timestamp, or a delivery window that restricts sends to chosen hours. - [Send a Message Digest](https://www.courier.com/docs/platform/sending/digest-send.md): Aggregate multiple notifications into one scheduled digest so users get a single summary instead of separate messages. - [Send Limits](https://www.courier.com/docs/platform/sending/send-limits.md): Cap message volume by user, topic, or tenant across time periods to ensure compliance, reduce overload, and protect delivery reliabilit… - [Channel Settings](https://www.courier.com/docs/platform/sending/channel-settings.md): Control per-channel delivery in Courier: set Always/Best-Of routing, disable channels, add send conditions, and manage provider integra… - [Channel Priority](https://www.courier.com/docs/platform/sending/channel-priority.md): Set a top-down channel and provider priority in Courier. Use Always Send for critical alerts and let user preferences override routing… - [Delivery Reliability and Retries](https://www.courier.com/docs/platform/sending/delivery-pipeline-resilience.md): Courier retries failed sends for up to 24 hours using exponential backoff, ensuring delivery through provider outages, rate limits, and… - [Automated Failover](https://www.courier.com/docs/platform/sending/failover.md): Configure failover so Courier reroutes messages on 408, 429, or 5xx errors. Set custom timeouts at the message, channel, and provider l… - [What are Templates?](https://www.courier.com/docs/platform/content/content-overview.md): Templates define a notification's content, structure, and behavior across channels. Build them visually in Template Designer or via the… - [Create and Edit Templates via API](https://www.courier.com/docs/platform/content/templates-api.md): Create, update, publish, and read multichannel notification templates over Courier's /notifications API. - [Design Studio Overview](https://www.courier.com/docs/platform/content/design-studio/design-studio-overview.md): Build multi-channel notifications with Design Studio, featuring reusable routing, version history, and an improved editing experience. - [Content Blocks](https://www.courier.com/docs/platform/content/design-studio/design-studio-block-basics.md): Drag heading, text, image, button, spacer, divider, and HTML blocks onto the canvas to build notifications in Design Studio, then reord… - [Heading Blocks](https://www.courier.com/docs/platform/content/d […gekürzt]