Send or schedule a message

Apps that only listen can be useful, but there's so much more utility to explore by transforming a monologue into a conversation. Give your app the gift of dialogue by setting it up to send Slack messages.

This guide will help you learn a basic way to accomplish this and show you the paths you can take to make things complex and interactive.

Sending messages

If you don't have a Slack app yet, here's a guide to help you create one. Make sure you create the app in a workspace that won't mind you posting lots of test messages.

Once you've done that, come back here and keep reading.

Requesting the necessary permissions

Each Slack app starts off without permission to do very much at all. You will have to grant your app the correct scopes required in order for you to publish messages. There are lots of scopes available, and you can read our OAuth guide for more information on why they're needed, and what they do.

For the purposes of this guide, however, we'll skip over that and just tell you the permissions we need right now.

The first is channels:read. That scope lets your app retrieve a list of all the public channels in a workspace so that you can pick one to publish a message to. If you already know the ID of the channel you wish to send messages to, you can skip out on requesting channels:read.

The second is chat:write. This one grants permission for your app to send messages as itself (apps can send messages as users or bot users, but we'll cover that later).

To request permissions:

1. Open the settings for your app from the App Management page.
2. In the navigation menu, select OAuth & Permissions.
3. Scroll down to the Scopes section, and pick channels:read and chat:write from the drop-down menu.
4. Click Save changes.
5. Scroll back to the top of this page and look for the button that says Install App to Workspace (or Reinstall App if you've done this before). Click it. You'll now see a permission request screen to install your app to its original workspace.

If you had already installed your app to its original workspace before, you might still see the permissions screen if the scopes you just added weren't previously granted to your app.

Authorize your app, and you should see a success message. On the OAuth & Permissions page you're brought back to, you should now see an OAuth access token available. Grab this token and store it for later, as we'll use that token to make some Web API calls.

Picking the right conversation

Now we need to find somewhere within your workspace to send a message. This could be any Slack conversation, but we'll use a public channel.

We'll remind you again, it's not a good idea to attempt the instructions in this guide with a real, living workspace. If you really have to, at least create a new, empty public channel within the workspace for testing purposes.

In order to find a valid Slack conversation ID, we'll use the conversations.list API method. This API will return a list of all public channels in the workspace your app is installed to. You'll need the channels:read permission granted to your app.

Within that list, we'll be able to find a specific id of the conversation that we want to access. Here's an example API call:

import com.slack.api.Slack;
import com.slack.api.methods.SlackApiException;
import com.slack.api.model.Conversation;
import org.slf4j.LoggerFactory;

import java.io.IOException;

public class FindingConversation {

    /**
     * Find conversation ID using the conversations.list method
     */
    static void findConversation(String name) {
        // you can get this instance via ctx.client() in a Bolt app
        var client = Slack.getInstance().methods();
        var logger = LoggerFactory.getLogger("my-awesome-slack-app");
        try {
            // Call the conversations.list method using the built-in WebClient
            var result = client.conversationsList(r -> r
                // The token you used to initialize your app
                .token(System.getenv("SLACK_BOT_TOKEN"))
            );
            for (Conversation channel : result.getChannels()) {
                if (channel.getName().equals(name)) {
                    var conversationId = channel.getId();
                    // Print result
                    logger.info("Found conversation ID: {}", conversationId);
                    // Break from for loop
                    break;
                }
            }
        } catch (IOException | SlackApiException e) {
            logger.error("error: {}", e.getMessage(), e);
        }
    }

    public static void main(String[] args) throws Exception {
        // Find conversation with a specified channel `name`
        findConversation("tester-channel");
    }

}

Code to initialize Bolt app
// Require the Node Slack SDK package (github.com/slackapi/node-slack-sdk)
const { WebClient, LogLevel } = require("@slack/web-api");

// WebClient instantiates a client that can call API methods
// When using Bolt, you can use either `app.client` or the `client` passed to listeners.
const client = new WebClient("xoxb-your-token", {
  // LogLevel can be imported and used to make debugging simpler
  logLevel: LogLevel.DEBUG
});
// Find conversation ID using the conversations.list method
async function findConversation(name) {
  try {
    // Call the conversations.list method using the built-in WebClient
    const result = await app.client.conversations.list({
      // The token you used to initialize your app
      token: "xoxb-your-token"
    });

    for (const channel of result.channels) {
      if (channel.name === name) {
        conversationId = channel.id;

        // Print result
        console.log("Found conversation ID: " + conversationId);
        // Break from for loop
        break;
      }
    }
  }
  catch (error) {
    console.error(error);
  }
}

// Find conversation with a specified channel `name`
findConversation("tester-channel");

Code to initialize Bolt app
import logging
import os
# Import WebClient from Python SDK (github.com/slackapi/python-slack-sdk)
from slack_sdk import WebClient
from slack_sdk.errors import SlackApiError

# WebClient instantiates a client that can call API methods
# When using Bolt, you can use either `app.client` or the `client` passed to listeners.
client = WebClient(token=os.environ.get("SLACK_BOT_TOKEN"))
logger = logging.getLogger(__name__)
channel_name = "needle"
conversation_id = None
try:
    # Call the conversations.list method using the WebClient
    for result in client.conversations_list():
        if conversation_id is not None:
            break
        for channel in result["channels"]:
            if channel["name"] == channel_name:
                conversation_id = channel["id"]
                #Print result
                print(f"Found conversation ID: {conversation_id}")
                break

except SlackApiError as e:
    print(f"Error: {e}")
    

GET https://slack.com/api/conversations.list
Authorization: Bearer xoxb-your-token

You'll get back a JSON object, with a channels array containing all the public channels that your app can see. You can find your channel by looking for the name in each object.

When you've found the matching channel, make note of the id value, as you'll need it for certain API calls.

Now that we've picked a destination, we need to decide what our message will look like.

Composing your message

Designing a message is a complicated topic, so we've broken it out into its own section that you can read at your leisure.

For this guide, we'll just publish a plain-text message. Here's the message payload we're going to send:

{
  "channel": "YOUR_CHANNEL_ID",
  "text": "Hello, world"
}

That seems appropriate, right? Let's get down to the actual business of sending this message.

Publishing your message

We're nearly there; we just need to make one more API call, this time to chat.postMessage. Again, substitute in the values of the token and conversation ID that you noted earlier:

import com.slack.api.Slack;
import com.slack.api.methods.SlackApiException;
import org.slf4j.LoggerFactory;

import java.io.IOException;

public class PublishingMessage {

    /**
     * Post a message to a channel your app is in using ID and message text
     */
    static void publishMessage(String id, String text) {
        // you can get this instance via ctx.client() in a Bolt app
        var client = Slack.getInstance().methods();
        var logger = LoggerFactory.getLogger("my-awesome-slack-app");
        try {
            // Call the chat.postMessage method using the built-in WebClient
            var result = client.chatPostMessage(r -> r
                // The token you used to initialize your app
                .token("xoxb-your-token")
                .channel(id)
                .text(text)
                // You could also use a blocks[] array to send richer content
            );
            // Print result, which includes information about the message (like TS)
            logger.info("result {}", result);
        } catch (IOException | SlackApiException e) {
            logger.error("error: {}", e.getMessage(), e);
        }
    }

    public static void main(String[] args) throws Exception {
        publishMessage("C12345", "Hello world :tada:");
    }

}

Code to initialize Bolt app
// Require the Node Slack SDK package (github.com/slackapi/node-slack-sdk)
const { WebClient, LogLevel } = require("@slack/web-api");

// WebClient instantiates a client that can call API methods
// When using Bolt, you can use either `app.client` or the `client` passed to listeners.
const client = new WebClient("xoxb-your-token", {
  // LogLevel can be imported and used to make debugging simpler
  logLevel: LogLevel.DEBUG
});
// Post a message to a channel your app is in using ID and message text
async function publishMessage(id, text) {
  try {
    // Call the chat.postMessage method using the built-in WebClient
    const result = await app.client.chat.postMessage({
      // The token you used to initialize your app
      token: "xoxb-your-token",
      channel: id,
      text: text
      // You could also use a blocks[] array to send richer content
    });

    // Print result, which includes information about the message (like TS)
    console.log(result);
  }
  catch (error) {
    console.error(error);
  }
}

publishMessage("C12345", "Hello world :tada:");

Code to initialize Bolt app
import logging
import os
# Import WebClient from Python SDK (github.com/slackapi/python-slack-sdk)
from slack_sdk import WebClient
from slack_sdk.errors import SlackApiError

# WebClient instantiates a client that can call API methods
# When using Bolt, you can use either `app.client` or the `client` passed to listeners.
client = WebClient(token=os.environ.get("SLACK_BOT_TOKEN"))
logger = logging.getLogger(__name__)
# ID of channel you want to post message to
channel_id = "C01JASD6802"

try:
    # Call the conversations.list method using the WebClient
    result = client.chat_postMessage(
        channel=channel_id,
        text="Hello world!"
        # You could also use a blocks[] array to send richer content
    )
    # Print result, which includes information about the message (like TS)
    print(result)

except SlackApiError as e:
    print(f"Error: {e}")
    

POST https://slack.com/api/chat.postMessage
Content-type: application/json
Authorization: Bearer xoxb-your-token
{
  "channel": "YOUR_CHANNEL_ID",
  "text": "Hello world :tada:"
}

This time we're using a POST request, so your token from before has to be included in the header of the request as a bearer token.

Submit the request and your message should be delivered instantly. You'll get back a response payload containing an ok confirmation value of true, and other data such as the channel the message was posted to. One very important piece of information in this response is the ts value, which is essentially the ID of the message, and which you'll need if you want to reply to this message.

Locate the Slack conversation the message was sent to and it should be waiting for you:

Amazing work! You've now implemented one of the core pieces of functionality for any Slack app. Keep reading to see how you can add a little more complexity.

Replying to your message

In some cases, you might find it more useful for your app to reply to another message, creating a thread. For example, if your app is sending a message in response to being mentioned, then it makes sense to add a threaded reply to the source of the mention.

Make sure the message you want to reply to isn't a reply itself, as shown in our retrieving messages guide.

For this guide, we'll assume the message is an unthreaded one. In fact, let's reply to the message you just published. You need three pieces of information to reply in a thread:

• An access token with the right permissions, like the token created earlier.
• The channel that the parent message lives in.
• The ts value of the parent message.

You should still have the last two pieces of information from the response payload you received after publishing the parent message.

In more generic terms, you can also find the ts value of messages by following our guide to retrieving individual messages.

Pulling all that data together, we can make another chat.postMessage API call to publish a reply:

import com.slack.api.Slack;
import com.slack.api.methods.SlackApiException;
import org.slf4j.LoggerFactory;

import java.io.IOException;

public class ReplyingMessage {

    /**
     * Reply to a message with the channel ID and message TS
     */
    static void replyMessage(String id, String ts) {
        // you can get this instance via ctx.client() in a Bolt app
        var client = Slack.getInstance().methods();
        var logger = LoggerFactory.getLogger("my-awesome-slack-app");
        try {
            // Call the chat.postMessage method using the built-in WebClient
            var result = client.chatPostMessage(r -> r
                // The token you used to initialize your app
                .token("xoxb-your-token")
                .channel(id)
                .threadTs(ts)
                .text("Hello again :wave:")
                // You could also use a blocks[] array to send richer content
            );
            // Print result
            logger.info("result {}", result);
        } catch (IOException | SlackApiException e) {
            logger.error("error: {}", e.getMessage(), e);
        }
    }

    public static void main(String[] args) throws Exception {
        // Uses a known channel ID and message TS
        replyMessage("C12345", "15712345.001500");
    }

}

Code to initialize Bolt app
// Require the Node Slack SDK package (github.com/slackapi/node-slack-sdk)
const { WebClient, LogLevel } = require("@slack/web-api");

// WebClient instantiates a client that can call API methods
// When using Bolt, you can use either `app.client` or the `client` passed to listeners.
const client = new WebClient("xoxb-your-token", {
  // LogLevel can be imported and used to make debugging simpler
  logLevel: LogLevel.DEBUG
});
// Reply to a message with the channel ID and message TS
async function replyMessage(id, ts) {
  try {
    // Call the chat.postMessage method using the built-in WebClient
    const result = await app.client.chat.postMessage({
      // The token you used to initialize your app
      token: "xoxb-your-token",
      channel: id,
      thread_ts: ts,
      text: "Hello again :wave:"
      // You could also use a blocks[] array to send richer content
    });

    // Print result
    console.log(result);
  }
  catch (error) {
    console.error(error);
  }
}

// Uses a known channel ID and message TS
replyMessage("C12345", "15712345.001500");

Code to initialize Bolt app
import logging
import os
# Import WebClient from Python SDK (github.com/slackapi/python-slack-sdk)
from slack_sdk import WebClient
from slack_sdk.errors import SlackApiError

# WebClient instantiates a client that can call API methods
# When using Bolt, you can use either `app.client` or the `client` passed to listeners.
client = WebClient(token=os.environ.get("SLACK_BOT_TOKEN"))
logger = logging.getLogger(__name__)
# TS of message you want to post thread to
message_ts = "1610144875.000600"

# ID of channel you want to post message to
channel_id = "C01JASD6802"

try:
    # Call the chat.postMessage method using the WebClient
    # The client passes the token you included in initialization    
    result = client.chat_postMessage(
        channel=channel_id,
        thread_ts=message_ts,
        text="Hello again :wave:"
        # You could also use a blocks[] array to send richer content
    )

    print(result)

except SlackApiError as e:
    print(f"Error: {e}")
    

POST https://slack.com/api/chat.postMessage
Content-type: application/json
Authorization: Bearer xoxb-your-token
{
  "channel": "YOUR_CHANNEL_ID",
  "thread_ts": "PARENT_MESSAGE_TS",
  "text": "Hello again!"
}

You'll see another API response payload containing information about the newly published threaded reply. Return to the same conversation in Slack, and you'll see your original message now has a reply:

When publishing threaded reply messages, you can also supply a reply_broadcast boolean parameter, as listed in the relevant API docs. This parameter, if set to true, will 'broadcast' a reference to the threaded reply to the parent conversation. Read more about the Slack user-facing equivalent of this feature here.

Sending messages as other entities

Apps can publish messages that appear to have been created by a user in the conversation. The message will be attributed to the user and show their profile photo beside it.

This is a powerful ability and must only be used when the user themselves gives permission to do so. For this reason, this ability is only available when an app has requested and been granted an additional scope — chat:write.customize.

Your app should only use this feature in response to an inciting user action. It should never be unexpected or surprising to a user that a message was posted on their behalf, and it should be heavily signposted in advance.

To modify the appearance of the app, make calls to chat.postMessage while providing any of the following parameters:

• username to specify the username for the published message.
• icon_url to specify a URL to an image to use as the profile photo alongside the message.
• icon_emoji to specify an emoji (using colon shortcodes, eg. :white_check_mark:) to use as the profile photo alongside the message.

If the channel parameter is set to a User ID (beginning with U), the message will appear in that user's direct message channel with Slackbot. To post a message to that user's direct message channel with the app, use the DM ID (beginning with D) instead.

Scheduling messages

Scheduling a message is just a bit of fancy footwork on top of sending a message directly. One thing you'll need before starting is a Slack app. If you don't have one yet, here's a very quick guide to help you create one. Make sure you create the app in a workspace that won't mind you posting lots of test messages!

Permissions

Now for some particularly pleasant permissions news: your app's permissions are actually the ones you've already acquired to post messages!

Let’s quickly recap. Your app uses a bot token to perform actions as itself. You grant your app permission to perform specific actions by giving its bot token the corresponding scopes.

For your app to send scheduled messages, it only needs one scope: chat:write.

If you don't already know the ID of the channel you wish to send messages to, you may also want to give your app another scope: channels:read. This scope lets your app retrieve a list of all the public channels in a workspace so you can pick one to publish a message to.

Schedule a message

Our guide to directly sending messages talked you through a call to chat.postMessage. Let's reinvent our app to send a reminder instead: say, about a weekly team breakfast.

{
  "channel": "YOUR_CHANNEL_ID",
  "text": "Hey, team. Don't forget about breakfast catered by John Hughes Bistro today."
}

If you want to do things the hard way, your app could implement state storage and job scheduling to send this message at the right time each week, using a database and batch task runner.

If you prefer an easier approach, use a scheduled message instead. Add a post_at parameter to your JSON request, and pass your JSON to chat.scheduleMessage instead of chat.postMessage:

import com.slack.api.bolt.App;
import com.slack.api.bolt.AppConfig;
import com.slack.api.bolt.jetty.SlackAppServer;
import com.slack.api.methods.SlackApiException;

import java.io.IOException;
import java.time.ZonedDateTime;
import java.time.temporal.ChronoUnit;

public class ChatScheduleMessage {

    public static void main(String[] args) throws Exception {
        var config = new AppConfig();
        config.setSingleTeamBotToken(System.getenv("SLACK_BOT_TOKEN"));
        config.setSigningSecret(System.getenv("SLACK_SIGNING_SECRET"));
        var app = new App(config); // `new App()` does the same

        app.command("/schedule", (req, ctx) -> {
            var logger = ctx.logger;
            var tomorrow = ZonedDateTime.now().truncatedTo(ChronoUnit.DAYS).plusDays(1).withHour(9);
            try {
                var payload = req.getPayload();
                // Call the chat.scheduleMessage method using the built-in WebClient
                var result = ctx.client().chatScheduleMessage(r -> r
                    // The token you used to initialize your app
                    .token(ctx.getBotToken())
                    .channel(payload.getChannelId())
                    .text(payload.getText())
                    // Time to post message, in Unix Epoch timestamp format
                    .postAt((int) tomorrow.toInstant().getEpochSecond())
                );
                // Print result
                logger.info("result: {}", result);
            } catch (IOException | SlackApiException e) {
                logger.error("error: {}", e.getMessage(), e);
            }
            // Acknowledge incoming command event
            return ctx.ack();
        });

        var server = new SlackAppServer(app);
        server.start();
    }

}

Code to initialize Bolt app
// Require the Node Slack SDK package (github.com/slackapi/node-slack-sdk)
const { WebClient, LogLevel } = require("@slack/web-api");

// WebClient instantiates a client that can call API methods
// When using Bolt, you can use either `app.client` or the `client` passed to listeners.
const client = new WebClient("xoxb-your-token", {
  // LogLevel can be imported and used to make debugging simpler
  logLevel: LogLevel.DEBUG
});
// Unix timestamp for tomorrow morning at 9AM
const tomorrow = new Date();
tomorrow.setDate(tomorrow.getDate() + 1);
tomorrow.setHours(9, 0, 0);

// Channel you want to post the message to
const channelId = "C12345";

try {
  // Call the chat.scheduleMessage method using the WebClient
  const result = await client.chat.scheduleMessage({
    channel: channelId,
    text: "Looking towards the future",
    // Time to post message, in Unix Epoch timestamp format
    post_at: tomorrow.getTime() / 1000
  });

  console.log(result);
}
catch (error) {
  console.error(error);
}

Code to initialize Bolt app
import datetime
import logging
import os
# Import WebClient from Python SDK (github.com/slackapi/python-slack-sdk)
from slack_sdk import WebClient
from slack_sdk.errors import SlackApiError

# WebClient instantiates a client that can call API methods
# When using Bolt, you can use either `app.client` or the `client` passed to listeners.
client = WebClient(token=os.environ.get("SLACK_BOT_TOKEN"))
logger = logging.getLogger(__name__)
# Create a timestamp for tomorrow at 9AM
tomorrow = datetime.date.today() + datetime.timedelta(days=1)
scheduled_time = datetime.time(hour=9, minute=30)
schedule_timestamp = datetime.datetime.combine(tomorrow, scheduled_time).strftime('%s')

# Channel you want to post message to
channel_id = "C12345"

try:
    # Call the chat.scheduleMessage method using the WebClient
    result = client.chat_scheduleMessage(
        channel=channel_id,
        text="Looking towards the future",
        post_at=schedule_timestamp
    )
    # Log the result
    logger.info(result)

except SlackApiError as e:
    logger.error("Error scheduling message: {}".format(e))

POST https://slack.com/api/chat.scheduleMessage
Content-type: application/json
Authorization: Bearer xoxb-your-token
{
  "channel": "YOUR_CHANNEL_ID",
  "text": "Hey, team. Don't forget about breakfast catered by John Hughes Bistro today.",
  "post_at": 1551891428,
}

Then sit back and relax. Like magic, the message appears at the moment specified in the post_at Unix timestamp.

The HTTP response from chat.scheduleMessage includes a scheduled_message_id, which can be used to delete the scheduled message before it is sent. Read on to find out how.

List your scheduled messages

"Fire and forget" reminders are all well and good, but the best-laid breakfast plans sometimes fall through. Let's say a holiday closes the office during one of your team's scheduled breakfast clubs. Better cancel that reminder message!

Your app can list all the messages that it currently has scheduled with the chat.scheduledMessages.list endpoint.

Call chat.scheduledMessages.list with optional channel, latest, and oldest parameters to specify which channel and time range you're interested in:

import com.slack.api.Slack;
import com.slack.api.methods.SlackApiException;
import org.slf4j.LoggerFactory;

import java.io.IOException;

public class ChatScheduledMessagesList {

    /**
     * Lists scheduled messages using latest and oldest timestamps
     */
    static void listScheduledMessages(String latest, String oldest) {
        // you can get this instance via ctx.client() in a Bolt app
        var client = Slack.getInstance().methods();
        var logger = LoggerFactory.getLogger("my-awesome-slack-app");
        try {
            // Call the chat.scheduledMessages.list method using the built-in WebClient
            var result = client.chatScheduledMessagesList(r -> r
                // The token you used to initialize your app
                .token(System.getenv("SLACK_BOT_TOKEN"))
                .latest(latest)
                .oldest(oldest)
            );
            // Print scheduled messages
            for (var message : result.getScheduledMessages()) {
                logger.info("message: {}", message);
            }
            // Print result
            logger.info("result: {}", result);
        } catch (IOException | SlackApiException e) {
            logger.error("error: {}", e.getMessage(), e);
        }
    }

    public static void main(String[] args) throws Exception {
        listScheduledMessages("1551991429", "1551991427");
    }

}

Code to initialize Bolt app
// Require the Node Slack SDK package (github.com/slackapi/node-slack-sdk)
const { WebClient, LogLevel } = require("@slack/web-api");

// WebClient instantiates a client that can call API methods
// When using Bolt, you can use either `app.client` or the `client` passed to listeners.
const client = new WebClient("xoxb-your-token", {
  // LogLevel can be imported and used to make debugging simpler
  logLevel: LogLevel.DEBUG
});
// List scheduled messages using latest and oldest timestamps
async function listScheduledMessages(latest, oldest) {
  try {
    // Call the chat.scheduledMessages.list method using the WebClient
    const result = await client.chat.scheduledMessages.list({
      latest: latest,
      oldest: oldest
    });

    // Print scheduled messages
    for (const message of result.scheduled_messages) {
      console.log(message);
    }
  }
  catch (error) {
    console.error(error);
  }
}

listScheduledMessages("1551991429", "2661991427");

Code to initialize Bolt app
import os
import logging
from slack_sdk.errors import SlackApiError
from slack_sdk.web import WebClient

client = WebClient(token=os.environ["SLACK_BOT_TOKEN"])
logger = logging.getLogger(__name__)

# List scheduled messages using latest and oldest timestamps
def list_scheduled_messages(latest, oldest):
    try:
        # Call the chat.scheduledMessages.list method using the WebClient
        result = client.chat_scheduledMessages_list(
            latest=latest, 
            oldest=oldest
        )

        # Print scheduled messages
        for message in result["scheduled_messages"]:
            logger.info(message)

    except SlackApiError as e:
        logger.error("Error creating conversation: {}".format(e))


list_scheduled_messages("1551991429", "2661991427")

POST https://slack.com/api/chat.scheduledMessages.list
Content-type: application/json
Authorization: Bearer xoxb-your-token
{
    "channel": "YOUR_CHANNEL_ID",
    "latest": 1551991429,
    "oldest": 1551991427,
}

oldest signifies the Unix timestamp of the earliest range you're interested in. latest signifies, well, the latest. So oldest must be less than latest if both are specified.

The endpoint yields scheduled messages sent by your app, plus pagination information.

{
    "ok": true,
    "scheduled_messages": [
        {
            "id": "YOUR_SCHEDULED_MESSAGE_ID",
            "channel_id": "YOUR_CHANNEL_ID",
            "post_at": 1551991428,
            "date_created": 1551891734
        }
    ],
    "response_metadata": {
        "next_cursor": ""
    }
}

Now that you've got the id of the breakfast club reminder you want to delete, one more method call awaits, so read on.

Delete a scheduled message

With the scheduled_message_id that you need in hand, it's time to banish that breakfast reminder. Use the chat.deleteScheduledMessage endpoint:

import com.slack.api.Slack;
import com.slack.api.methods.SlackApiException;
import org.slf4j.LoggerFactory;

import java.io.IOException;

public class ChatDeleteScheduledMessage {

    /**
     * Deletes scheduled message using channel ID and scheduled message ID
     */
    static void deleteScheduledMessage(String channel, String id) {
        // you can get this instance via ctx.client() in a Bolt app
        var client = Slack.getInstance().methods();
        var logger = LoggerFactory.getLogger("my-awesome-slack-app");
        try {
            var result = client.chatDeleteScheduledMessage(r -> r
                // The token you used to initialize your app
                .token(System.getenv("SLACK_BOT_TOKEN"))
                .channel(channel)
                .scheduledMessageId(id)
            );
            // Print result
            logger.info("result: {}", result);
        } catch (IOException | SlackApiException e) {
            logger.error("error: {}", e.getMessage(), e);
        }
    }

    public static void main(String[] args) throws Exception {
        deleteScheduledMessage("C12345", "Q123ABC95");
    }

}

Code to initialize Bolt app
// Require the Node Slack SDK package (github.com/slackapi/node-slack-sdk)
const { WebClient, LogLevel } = require("@slack/web-api");

// WebClient instantiates a client that can call API methods
// When using Bolt, you can use either `app.client` or the `client` passed to listeners.
const client = new WebClient("xoxb-your-token", {
  // LogLevel can be imported and used to make debugging simpler
  logLevel: LogLevel.DEBUG
});
// The ts of the message you want to delete
const messageId = "U12345";
// ID of channel that the scheduled message was sent to
const channelId = "C12345";

try {
  // Call the chat.deleteScheduledMessage method using the WebClient
  const result = await client.chat.deleteScheduledMessage({
    channel: channelId,
    scheduled_message_id: messageId
  });

  console.log(result);
}
catch (error) {
  console.error(error);
}

Code to initialize Bolt app
import logging
import os
# Import WebClient from Python SDK (github.com/slackapi/python-slack-sdk)
from slack_sdk import WebClient
from slack_sdk.errors import SlackApiError

# WebClient instantiates a client that can call API methods
# When using Bolt, you can use either `app.client` or the `client` passed to listeners.
client = WebClient(token=os.environ.get("SLACK_BOT_TOKEN"))
logger = logging.getLogger(__name__)
# The ts of the message you want to delete
message_id = "U12345"
# ID of channel that the scheduled message was sent to
channel_id = "C12345"

try:
    # Call the chat.deleteScheduledMessage method using the built-in WebClient
    result = client.chat_deleteScheduledMessage(
        channel=channel_id,
        scheduled_message_id=message_id
    )
    # Log the result
    logger.info(result)

except SlackApiError as e:
    logger.error(f"Error deleting scheduled message: {e}")

POST https://slack.com/api/chat.deleteScheduledMessage
Content-type: application/json
Authorization: Bearer xoxb-your-token
{
    "channel": "YOUR_CHANNEL_ID",
    "scheduled_message_id": "YOUR_SCHEDULED_MESSAGE_ID"
}

You'll receive the typical success response once your scheduled message has been deleted.

Update a scheduled message

To update a pending scheduled message, delete the old message and then schedule a new one.

Reminders, notifications, even calendars—all now fall within grasp of your app. You don't have to store any state at all if you don't wish to. Instead, list and delete your scheduled messages on the fly. Combine scheduled messages with user interactivity to create a chat bot that's a capable, clever assistant. Enjoy the newfound simplicity of scheduled messages!