Courier C# SDK

The Courier C# SDK gives typed access to the from C#. It targets .NET Standard 2.0, uses async/await throughout, and returns typed response objects. Available on NuGet and GitHub.

Installation

Install the package from NuGet:

dotnet add package TryCourier

Requires .NET Standard 2.0 or later.

Quick start

using System.Text.Json;
using TryCourier;
using TryCourier.Models;
using TryCourier.Models.Send;

CourierClient client = new();

var response = await client.Send.Message(new SendMessageParams
{
    Message = new()
    {
        To = new UserRecipient { UserId = "user_123" },
        Template = "welcome-email",
        Data = new Dictionary<string, JsonElement>
        {
            { "name", JsonSerializer.SerializeToElement("Sarah Bennett") },
        },
    },
});

Console.WriteLine(response.RequestID);

The client reads COURIER_API_KEY from your environment. You can also set it explicitly: new CourierClient { ApiKey = "YOUR_COURIER_API_KEY" }.

Authentication

Get your API key from . Set it as an environment variable:

export COURIER_API_KEY="YOUR_COURIER_API_KEY"

Or pass it to the client:

CourierClient client = new() { ApiKey = "YOUR_COURIER_API_KEY" };

Property	Environment variable	Default
`ApiKey`	`COURIER_API_KEY`	—
`BaseUrl`	`COURIER_BASE_URL`	`https://api.courier.com`

Sending notifications

Design your notification in , then reference it by ID:

var response = await client.Send.Message(new SendMessageParams
{
    Message = new()
    {
        To = new UserRecipient { UserId = "user_123" },
        Template = "my-template-id",
        Data = new Dictionary<string, JsonElement>
        {
            { "order_id", JsonSerializer.SerializeToElement("10042") },
        },
    },
});

Available resources

The SDK covers the full Courier API. Every method is async and returns typed models.

Resource	Namespace	Description
Send	`client.Send`	Send messages to one or more recipients
Messages	`client.Messages`	Retrieve status, history, and content of sent messages
Profiles	`client.Profiles`	Create, update, and retrieve user profiles
Users	`client.Users`	Manage preferences, tenants, and push tokens per user
Auth	`client.Auth`	Issue JWT tokens for client-side SDK authentication
Lists	`client.Lists`	Manage subscription lists and their subscribers
Audiences	`client.Audiences`	Define and query audience segments
Tenants	`client.Tenants`	Manage tenants for multi-tenant setups
Journeys	`client.Journeys`	Invoke and cancel runs. Create, list, publish, and archive
Brands	`client.Brands`	Manage brand settings (logos, colors, templates)
Notifications	`client.Notifications`	List and inspect notification templates
Translations	`client.Translations`	Workspace `.po` strings for the `{{t}}` helper

Common operations

Checking message status

var message = await client.Messages.Retrieve("your-message-id");
Console.WriteLine(message.Status);
Console.WriteLine(message.Delivered);

Managing user profiles

await client.Profiles.Create("user_123", new ProfileCreateParams
{
    Profile = new Dictionary<string, JsonElement>
    {
        { "email", JsonSerializer.SerializeToElement("sarah@acme-corp.com") },
        { "name", JsonSerializer.SerializeToElement("Sarah Bennett") },
    },
});

var profile = await client.Profiles.Retrieve("user_123");

Issuing JWT tokens

Courier’s (React, JavaScript, mobile) authenticate users with a JWT your backend issues. covers the token flow, the scope strings, and token refresh. Use client.Auth.IssueToken:

var result = await client.Auth.IssueToken(new AuthIssueTokenParams
{
    Scope = "user_id:user_123 inbox:read:messages inbox:write:events",
    ExpiresIn = "2 days",
});

Console.WriteLine(result.Token);

Scope	Permission
`user_id:<id>`	Which user the token is for (required)
`inbox:read:messages`	Read inbox messages
`inbox:write:events`	Mark messages as read/archived
`read:preferences`	Read notification preferences
`write:preferences`	Update notification preferences
`write:user-tokens`	Register push notification tokens

Configuration

Error handling

When the API returns a non-success status code, the SDK throws a CourierApiException:

try
{
    await client.Send.Message(parameters);
}
catch (CourierApiException e)
{
    Console.WriteLine(e.StatusCode);
    Console.WriteLine(e.Message);
}

Retries and timeouts

The SDK retries failed requests up to 2 times with exponential backoff. Use WithOptions to configure per-request:

var response = await client
    .WithOptions(options => options with
    {
        Timeout = TimeSpan.FromSeconds(20),
        MaxRetries = 0,
    })
    .Send.Message(parameters);

WithOptions returns a new client instance. The original is unchanged.

Journeys

are multi-step workflows: send, delay, branch, throttle, digest, and more. Invoke one by ID or alias to start a run. Cancel runs by ID, or by a shared cancelation token.

// Start a run (by journey ID or alias); the response includes RunID
var response = await client.Journeys.Invoke("your-journey-id", new JourneyInvokeParams
{
    UserID = "user_123",
});
Console.WriteLine(response.RunID);

client.Journeys.Cancel(...) takes exactly one of run_id or cancelation_token (spelled with one “l”). Build and manage journeys from code with Create, List, Publish, and Archive. See .

More operations

A few more resources from the full :

Resource	Method	Use case
User preferences	`client.Users.Preferences.Retrieve(userId)`	Fetch a user’s notification preferences for your
Cancel a message	`client.Messages.Cancel(messageId)`	Cancel a delayed or queued message before delivery
Push tokens	`client.Users.Tokens.AddSingle(token, params)`	Register a device push token for , , , or

API Reference

Full REST API docs with request/response examples.

Send API

Learn about the Send endpoint, routing, and message options.

Quickstart

Send your first notification in under two minutes.

GitHub

Source code, issues, and changelog.

Idempotent sends

Pass an idempotency key and Courier replays the first response for that key instead of sending again. The SDK sets the Idempotency-Key header for you. covers the scoping rule and the replay window.

SendMessageParams parameters = new()
{
    Message = new() { To = new UserRecipient { UserId = "user_123" }, Template = "nt_01kx4h2jdafq8bk9aftxak4b40" },
    IdempotencyKey = "6f3b8c2a-9d4e-4b7a-a1c5-2e8f0d5b7a91",
};
var response = await client.Send.Message(parameters);

Get started

Server

Client

Installation

Quick start

Authentication

Sending notifications

Available resources

Common operations

Checking message status

Managing user profiles

Issuing JWT tokens

Configuration

Error handling

Retries and timeouts

Journeys

More operations

API Reference

Send API

Quickstart

GitHub

Idempotent sends

​Installation

​Quick start

​Authentication

​Sending notifications

​Available resources

​Common operations

​Checking message status

​Managing user profiles

​Issuing JWT tokens

​Configuration

​Error handling

​Retries and timeouts

​Journeys

​More operations

API Reference

Send API

Quickstart

GitHub

​Idempotent sends

Installation

Quick start

Authentication

Sending notifications

Available resources

Common operations

Checking message status

Managing user profiles

Issuing JWT tokens

Configuration

Error handling

Retries and timeouts

Journeys

More operations

Idempotent sends