EasySlack 1.0.1

EasySlack

<img src="assets/icon-grey.png" width="128" height="128" alt="EasySlack icon" />

EasySlack is a native C# Slack connector built directly on Slack Web API and Socket Mode. It avoids a dependency on a third-party Slack wrapper while providing a small, focused API for validation, sending messages, threaded replies, and receiving inbound Slack message events.

Projects

• src/EasySlack: class library containing the connector, auth/options models, Web API calls, and Socket Mode event handling
• src/EasySlackConsole: interactive console app using Inputty for manual Slack testing
• src/Test.Automated: console-based automated test runner with pass/fail output per test, suite summary, total runtime, and failed test enumeration

Current Capabilities

• Instantiate a connector from Slack auth material
• Validate bot-token connectivity using auth.test
• Send a message to a channel or conversation using chat.postMessage
• Send a threaded reply to a channel or conversation using thread_ts
• Send a message to a user by opening a direct conversation with conversations.open
• Retrieve basic conversation metadata with conversations.info
• Retrieve basic user metadata with users.info
• Receive Socket Mode message events over WebSocket
• Surface inbound thread_ts for threaded message handling
• Fire async events for:
  • message received
  • connected
  • disconnected
  • action required

Slack App Setup

Start at https://api.slack.com/apps/ and create a new Slack app From scratch.

For the current version of EasySlack, the runtime only needs:

• a bot token starting with xoxb-
• an app-level token starting with xapp-

1. Basic Information

After the app is created, open Basic Information.

This page contains several values commonly grouped together as "Slack auth information":

• App ID
• Client ID
• Client Secret
• Signing Secret
• Verification Token

What they are for:

• App ID: Slack's identifier for the app, usually A...
• Client ID: used in OAuth authorization flows
• Client Secret: used when exchanging OAuth authorization codes for tokens
• Signing Secret: used to verify inbound HTTP requests from Slack
• Verification Token: legacy compatibility value; Slack recommends the Signing Secret instead

EasySlack does not currently use those values directly at runtime, but you may need them later if you add distributed OAuth installs, HTTP-delivered Events API, slash commands, or interactivity.

While still on Basic Information, find App-Level Tokens and click Generate Token and Scopes.

Create an app-level token with:

• connections:write

Slack will issue a token starting with xapp-.

Use that value as:

• SlackAuthMaterial.AppToken

2. Set The App Icon

Still under Basic Information, go to Display Information and upload the app icon.

Recommended:

• use a square PNG
• use an icon that remains readable at small sizes

3. Enable Socket Mode

Open Socket Mode under Settings and enable it.

If you do not see Socket Mode, the app is likely not the right app type for this workflow. In practice, the cleanest fix is usually to create a fresh modern Slack app and configure it again from scratch.

Socket Mode means:

• Slack does not send events to your public web server
• your app opens an authenticated WebSocket connection to Slack
• Slack delivers Events API payloads over that WebSocket

4. Add OAuth Scopes

Open OAuth & Permissions and add these Bot Token Scopes:

• channels:history
• channels:read
• chat:write
• groups:history
• groups:read
• im:history
• im:read
• im:write
• mpim:history
• mpim:read
• mpim:write
• users:read

Optional but useful:

• chat:write.public
• app_mentions:read

What these scopes are for:

• Message subscription and read access:
  • channels:history
  • groups:history
  • im:history
  • mpim:history
• Metadata lookup:
  • channels:read
  • groups:read
  • im:read
  • mpim:read
  • users:read
• Sending messages:
  • chat:write
• Sending a direct message to a user via SendMessageToUserAsync:
  • im:write
• Multi-person DM creation or opening:
  • mpim:write
• Posting to public channels without first inviting the app:
  • chat:write.public
• Receiving @YourAppName mentions in channels:
  • app_mentions:read

Important:

• After changing scopes, click Reinstall to Workspace or the new scopes will not take effect.

5. Enable Event Subscriptions

Open Event Subscriptions under Features and enable them.

Important distinction:

• Socket Mode removes the need for a public inbound HTTP endpoint
• but you still must enable Event Subscriptions
• and you still must add the bot events you want Slack to deliver

When Socket Mode is enabled correctly, Slack should display a message similar to:

• Socket Mode is enabled. You won't need to specify a Request URL.

Under Subscribe to bot events, add the events you need:

• message.channels for public-channel messages
• message.groups for private-channel messages
• message.im for direct-message events
• message.mpim for multi-person direct-message events
• app_mention if you want the app to receive @YourAppName mentions in channels

Important distinction:

• message.channels is an event subscription, not a scope
• message.groups is an event subscription, not a scope
• message.im is an event subscription, not a scope
• message.mpim is an event subscription, not a scope
• app_mention is an event subscription, not a scope
• app_mentions:read is a scope

6. Install Or Reinstall The App

In the left navigation under Settings, click Install App, then click Install to Workspace or Reinstall to Workspace.

After approval, Slack generates the bot token shown as:

• Bot User OAuth Token

That token:

• usually starts with xoxb-
• is the token EasySlack uses for:
  • auth.test
  • chat.postMessage
  • conversations.info
  • conversations.open
  • users.info

Use that value as:

• SlackAuthMaterial.BotToken

7. Invite The App To Conversations

Installing the app gives it credentials, but it does not automatically make the app a member of every conversation.

This is the most common cause of errors such as:

• not_in_channel

For public channels:

• invite the app with /invite @YourAppName
• or grant chat:write.public if you want the app to post to public channels without being invited first

For private channels:

• the app must be explicitly invited
• chat:write.public does not help
• open the private channel and run:

/invite @YourAppName

For direct messages:

• SendMessageToUserAsync expects a user ID such as U...
• it does not expect a DM conversation ID such as D...
• the library opens or reuses the DM conversation automatically
• this requires im:write

How To Find Slack IDs

EasySlack methods generally work with Slack IDs rather than human-readable names.

Common ID prefixes:

• C...: public channel
• G...: private channel
• D...: direct-message conversation
• U...: user
• A...: app

How To Get A Channel ID

1. Open the channel in Slack
2. Look at the URL
3. The last path segment is usually the channel or conversation ID

Example:

• https://yourworkspace.slack.com/client/T12345678/C0123456789
• Channel ID: C0123456789

How To Get A User ID

1. Open the user's profile in Slack
2. Use Slack's copy-member-ID style action if your client exposes it
3. If that option is not visible, inspect profile-related links or user-detail surfaces where the U... identifier appears

Example:

• User ID: U0123456789

Important ID Usage Rules

• channel send expects a conversation ID such as C..., G..., or D...
• user send expects a user ID such as U...
• once a DM exists, Slack represents it as a conversation ID such as D...
• SendMessageToUserAsync avoids needing the D... ID up front because it accepts a U... user ID and opens or reuses the DM conversation

Getting Started

Create Slack auth material with your bot token and app token, then build a connector from it.

using EasySlack;
using System.Threading;

SlackAuthMaterial auth = new SlackAuthMaterial(
    "xoxb-your-bot-token",
    "xapp-your-app-token");

SlackConnectorOptions options = new SlackConnectorOptions(auth)
{
    AutoReconnect = true
};

using CancellationTokenSource cancellationTokenSource = new CancellationTokenSource();
using SlackConnector connector = new SlackConnector(options, cancellationTokenSource);

Subscribe To A Channel

The connector raises MessageReceived for plain inbound Slack message events delivered through Socket Mode. Messages with a non-empty Slack subtype are skipped by default. Filter to the channel you care about inside the handler.

using EasySlack;
using System;
using System.Threading;
using System.Threading.Tasks;

SlackAuthMaterial auth = new SlackAuthMaterial(
    "xoxb-your-bot-token",
    "xapp-your-app-token");

SlackConnectorOptions options = new SlackConnectorOptions(auth);

using CancellationTokenSource cancellationTokenSource = new CancellationTokenSource();
using SlackConnector connector = new SlackConnector(options, cancellationTokenSource);

string channelId = "C0123456789";

connector.MessageReceived += async (sender, eventArgs) =>
{
    if (eventArgs.ChannelId == channelId)
    {
        string conversationKey = eventArgs.ThreadTimestamp ?? eventArgs.Timestamp ?? string.Empty;

        Console.WriteLine("New message received.");
        Console.WriteLine("User: " + eventArgs.UserId);
        Console.WriteLine("Text: " + eventArgs.Text);
        Console.WriteLine("Timestamp: " + eventArgs.Timestamp);
        Console.WriteLine("Thread Timestamp: " + (eventArgs.ThreadTimestamp ?? "(top-level message)"));
        Console.WriteLine("Conversation Key: " + conversationKey);
    }

    await Task.CompletedTask.ConfigureAwait(false);
};

await connector.StartAsync(cancellationTokenSource.Token).ConfigureAwait(false);

Console.WriteLine("Listening for messages. Press ENTER to stop.");
Console.ReadLine();

await connector.StopAsync(cancellationTokenSource.Token).ConfigureAwait(false);

Send A Message To A User

To send a direct message to a user, pass the Slack user ID to SendMessageToUserAsync. The connector opens or reuses the direct-message conversation before posting the message.

using EasySlack;
using System;
using System.Threading;

SlackAuthMaterial auth = new SlackAuthMaterial(
    "xoxb-your-bot-token",
    "xapp-your-app-token");

SlackConnectorOptions options = new SlackConnectorOptions(auth);

using CancellationTokenSource cancellationTokenSource = new CancellationTokenSource();
using SlackConnector connector = new SlackConnector(options, cancellationTokenSource);

SlackSendMessageResult result = await connector
    .SendMessageToUserAsync("U0123456789", "Hello from EasySlack.", cancellationTokenSource.Token)
    .ConfigureAwait(false);

if (result.Ok)
{
    Console.WriteLine("Message sent.");
    Console.WriteLine("Conversation: " + result.ChannelId);
    Console.WriteLine("Timestamp: " + result.Timestamp);
}
else
{
    Console.WriteLine("Slack rejected the message: " + result.Error);
}

Send A Threaded Reply To A Conversation

To reply in an existing Slack thread, pass the channel or conversation ID plus the thread root timestamp to SendMessageToChannelAsync. Leave threadTimestamp empty to keep the existing top-level post behavior.

using EasySlack;
using System;
using System.Threading;

SlackAuthMaterial auth = new SlackAuthMaterial(
    "xoxb-your-bot-token",
    "xapp-your-app-token");

SlackConnectorOptions options = new SlackConnectorOptions(auth);

using CancellationTokenSource cancellationTokenSource = new CancellationTokenSource();
using SlackConnector connector = new SlackConnector(options, cancellationTokenSource);

connector.MessageReceived += async (sender, eventArgs) =>
{
    string replyThreadTimestamp = eventArgs.ThreadTimestamp ?? eventArgs.Timestamp ?? string.Empty;

    if (eventArgs.ChannelId == "C0123456789" && !string.IsNullOrWhiteSpace(replyThreadTimestamp))
    {
        await connector
            .SendMessageToChannelAsync(
                eventArgs.ChannelId,
                "Replying in the same thread.",
                replyThreadTimestamp,
                cancellationTokenSource.Token)
            .ConfigureAwait(false);
    }
};

For top-level Slack messages, ThreadTimestamp is usually null. Use eventArgs.ThreadTimestamp ?? eventArgs.Timestamp when you want a stable conversation key that works for both root posts and replies.

Build

cd C:\Code\EasySlack\src
dotnet build
dotnet run --project .\Test.Automated\Test.Automated.csproj --framework net8.0
dotnet run --project .\EasySlackConsole\EasySlackConsole.csproj --framework net8.0

Attribution

<a target="_blank" href="https://icons8.com/icon/OBMhWEebAWe9/slack-new">Slack New</a> icon by <a target="_blank" href="https://icons8.com">Icons8</a>