How to create Oauth2 credential for Slack

In this guide, I will walk you through the process of customising the auth config for Slack. So, let’s begin.

Setting up Slack

In this section, we’ll go through the process of setting up Slack and creating an OAuth2 application.

NOTE: If you already have a Slack app and access to the Client ID and Client Secret, you can skip this section.

Step 1: Create a Slack App

1. Go to the Slack API Dashboard and click Create New App.

1. Choose from scratch.

1. Enter your App Name (e.g., Composio Integration) and select your Slack workspace.

2. Click Create App.

Step 2: Configure OAuth & Permissions

Once the app is created, open the OAuth & Permissions section from the left sidebar.

Scroll down to the Redirect URLs section and click Add New Redirect URL.

Paste the following Composio callback URL:

https://backend.composio.dev/api/v3/toolkits/auth/callback

Click Add and then Save URLs.

Step 3: Add OAuth Scopes

Under the same OAuth & Permissions section, scroll to Scopes.

Slack scopes define what your app can do or access on behalf of a user.

You’ll need to select the scopes that match your integration’s functionality. For example:

• To read channel messages → channels:history

• To send messages → chat:write

• To read user info → users:read

Scopes Supported by Composio

Instead of manually guessing the scopes in Slack, use the scopes that Composio supports for Slack.

Scopes supported by Composio:

Below are all the scopes that Composio supports for Slack. You can select these based on your integration needs:

calls:read,calls:write,channels:read,channels:history,channels:write,chat:write,chat:write.public,emoji:read,files:read,files:write,groups:read,groups:history,groups:write,im:read,im:write,im:history,mpim:read,mpim:write,mpim:history,pins:read,pins:write,reactions:read,reactions:write,reminders:read,reminders:write,remote_files:read,remote_files:share,search:read,stars:read,stars:write,team:read,usergroups:read,usergroups:write,users:read,users:read.email,users:write,users.profile:read,users.profile:write,bookmarks:read,bookmarks:write,links:read,links:write

These define what actions your Slack integration can take.

Always include only the ones necessary for your workflow, for example, if your agent only needs to send messages, chat:write alone might be enough.

Note: Slack separates Bot Token Scopes (for app-level access) and User Token Scopes (for user-level actions). Composio typically uses Bot Token Scopes.

Step 4: Get Your OAuth Credentials

Once you've created your Slack app, you can find your OAuth credentials in the Basic Information section:

1. In the left sidebar, click Basic Information

2. Scroll down to the App Credentials section

3. You'll see:

Copy the Client ID and Client Secret, as you'll need them for Composio.

Creating the Auth Config in Composio

With your Slack credentials ready, navigate to the Composio Dashboard.

1. Click on Create Auth Config.

2. From the toolkit list, select Slack.

1. Ensure the authentication type is set to OAuth2.

2. Check Use your own developer authentication if using your custom Slack app.

1. Click Create Slack Auth Config.

Step 5: Fill in OAuth Details

In the Manage Auth Config section, fill in the fields:

• Client ID → from Slack app

• Client Secret → from Slack app

• Redirect URI →

• Scopes → use the Composio-supported scopes listed above

Click Create Slack Auth Config.

Base URL for Slack API

All Slack API calls are made via:

That’s it! Your Slack + Composio OAuth integration is ready.

You can now copy the Auth Config ID (ac_...) and use it inside your code or secret manager.