Slack Send Message

Sends messages to Slack channels or threads from a workflow. Use it for notifications, alerts, bot replies, and any programmatic messaging in Slack.

Requirements

This plugin requires a Slack bot token:

Create a Slack App at api.slack.com/apps
Add the chat:write OAuth scope
Install the app to your workspace
Add SLACK_BOT_TOKEN on the Env Vars page

Output

Handle	Type	Description
`result`	object	Slack message send result

The result (accessed as {{ slack_message.* }}) shape:

Field	Type	Description
`success`	boolean	Whether the message was sent successfully
`message_ts`	string	Timestamp of the sent message (use as `thread_ts` for replies)
`channel`	string	Channel ID where the message was posted
`error`	string	Error message if `success` is `false`

Settings

Setting	Type	Description
`channel`	string	Channel ID (e.g., `C01234ABCDE`) or name (e.g., `#general`). Supports `{{ }}` bindings.
`text`	string	Message text content. Supports `{{ }}` bindings.
`blocks`	JSON	Optional Block Kit JSON for rich formatting. Supports `{{ }}` bindings.
`thread_ts`	string	Thread timestamp to reply in a thread. Supports `{{ }}` bindings.

Authentication

Env Var	Description
`SLACK_BOT_TOKEN`	Bot User OAuth Token (`xoxb-...`) with `chat:write` scope

Example

Send a deployment alert to #alerts when a webhook fires:

Channel: #alerts
Text: Deployment succeeded for {{ webhook.body.service }} at {{ webhook.body.timestamp }}

Reply in a thread after a Slack Trigger:

Channel: {{ slack.channel }}
Text: Got it! Processing your request...
Thread Timestamp: {{ slack.timestamp }}

Block Kit

Use the Block Kit JSON field to send rich messages with sections, buttons, and images. Pass a valid Block Kit blocks array:

[
  {
    "type": "section",
    "text": {
      "type": "mrkdwn",
      "text": "*Deployment succeeded*\nService: `api-gateway`"
    }
  }
]

When blocks is provided, it takes priority over plain text for message formatting.

AI Agent Tool

Connect this node to an AI Agent as a tool. The agent can send Slack notifications on your behalf — for example, "notify #alerts that deployment succeeded" — using dynamic values from the conversation context.

Common Gotchas

Channel access: The bot must be invited to the channel before it can post. Use /invite @your-bot in the channel.
Thread replies: Set thread_ts to the parent message's timestamp. Use {{ slack.timestamp }} from a Slack Trigger to reply in the same thread.
Check slack_message.success: The node does not automatically stop execution on failure. Connect the On Error branch or add an If node to handle failures.
Missing SLACK_BOT_TOKEN: The node fails at runtime with an authentication error if the env var is not set.