Slack
Post messages to Slack channels from your agent's workflows using a Slack bot token.
The Slack connector lets your agent post messages to any channel in your Slack workspace. Messages can be plain text, Slack-flavoured markdown, or rich Block Kit layouts. You can also thread replies to an existing message.
What you can do
| Action | Node type | Description |
|---|---|---|
| Post a message | Slack Message | Post a message to a channel. Supports text, Slack markdown, Block Kit JSON, and threaded replies. |
All message fields support {{variable}} template syntax, so the channel and message body can be dynamically filled from earlier workflow steps.
Before you start
You need a Bot User OAuth Token from a Slack app installed in your workspace:
| Credential field | Description |
|---|---|
| Bot Token | The bot token from your Slack app (xoxb-...). Found under OAuth & Permissions after installing the app. |
| Default Channel | Optional. A fallback channel (e.g. #general) used when the workflow node doesn't specify one explicitly. |
The Slack app must have these Bot Token Scopes: chat:write, channels:read, groups:read.
Connect Slack
Create a Slack app.
Go to the Slack API portal and click Create New App. Choose From scratch, give your app a name, and select the workspace to install it to.
Add the required bot scopes.
Under OAuth & Permissions > Bot Token Scopes, add: chat:write, channels:read, groups:read.
Install the app to your workspace.
Click Install to Workspace and authorise. Copy the Bot User OAuth Token (starts with xoxb-).
Invite the bot to the channels it will post to.
In Slack, open the target channel and type /invite @YourBotName, or go to channel settings and add the bot under Integrations.
Enter the credentials in Mojar.
In your agent, open Integrations, find Slack, and click its card. Paste the Bot Token, optionally set a Default Channel, give the connection a name, and click Connect.
Click Verify Connection to confirm the bot token works before saving.
Use it in a workflow
Fill in the fields:
- Channel — the channel ID or name to post to, e.g.
{{workflow.slackChannel}}or#alerts - Message — the message text (supports Slack markdown and
{{variable}}syntax) - Blocks — optional Block Kit JSON for rich card layouts
- Thread timestamp — optional
thread_tsvalue to post the message as a reply in a thread
The bot must be a member of the channel before it can post. If the workflow fails with a not_in_channel error, invite the bot to that channel in Slack.