Sends an ephemeral message to a user in a channel.


Method access

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Content types

  • Rate limits

    Tier 4
  • Arguments

    Required arguments

    Authentication token bearing required scopes. Tokens should be passed as an HTTP Authorization header or alternatively, as a POST parameter.


    Channel, private group, or IM channel to send message to. Can be an encoded ID, or a name.


    id of the user who will receive the ephemeral message. The user should be in the channel specified by the channel argument.


    One of these arguments is required to describe the content of the message. If attachments or blocks are included, text will be used as fallback text for notifications only.

    A JSON-based array of structured attachments, presented as a URL-encoded string.

    [{"pretext": "pre-hello", "text": "text-world"}]

    A JSON-based array of structured blocks, presented as a URL-encoded string.

    [{"type": "section", "text": {"type": "plain_text", "text": "Hello world"}}]

    How this field works and whether it is required depends on other fields you use in your API call. See below for more detail.

    Hello world
    Optional arguments

    (Legacy) Pass true to post the message as the authed user. Defaults to true if the chat:write:bot scope is not included. Otherwise, defaults to false.


    Emoji to use as the icon for this message. Overrides icon_url.


    URL to an image to use as the icon for this message.


    Find and link channel names and usernames.


    Change how messages are treated. Defaults to none. See below.


    Provide another message's ts value to post this message in a thread. Avoid using a reply's ts value; use its parent's value instead. Ephemeral messages in threads are only shown if there is already an active thread.


    Set your bot's user name.

    My Bot

    Usage info

    This method posts an ephemeral message, which is visible only to the assigned user in a specific public channel, private channel, or private conversation.

    Ephemeral message delivery is not guaranteed β€” the user must be currently active in Slack and a member of the specified channel. By nature, ephemeral messages do not persist across reloads, desktop and mobile apps, or sessions. Once the session is closed, ephemeral messages will disappear and cannot be recovered.

    Use ephemeral messages to send users context-sensitive messages, relevant to the channel they're detectably participating in. Avoid sending unexpected or unsolicited ephemeral messages.

    text, blocks or attachments

    The usage of the text field changes depending on whether you're using blocks. If you're using blocks, this is used as a fallback string to display in notifications. If you aren't, this is the main body text of the message. It can be formatted as plain text, or with mrkdwn.

    The text field is not enforced as required when using blocks or attachments. However, we highly recommended that you include text to provide a fallback when using blocks, as described above.


    Messages are formatted as described in the formatting spec. You can specify values for parse and link_names to change formatting behavior.

    The optional attachments argument should contain a JSON-encoded array of attachments.

    For more information, see the attachments spec. If you're using a Slack app, you can also use this method to attach message buttons.

    For best results, limit the number of characters in the text field to a few thousand bytes at most. Ideally, messages should be short and human-readable, if you need to post longer messages, please consider uploading a snippet instead. (A single message should be no larger than 4,000 bytes.)

    Consider reviewing our message guidelines, especially if you're using attachments or message buttons.


    How message authorship is attributed varies by a few factors, with some behaviors varying depending on the kinds of tokens you're using to post a message.

    Legacy concerns

    Information in the section below applies only to classic Slack apps.

    Legacy authorship

    Classic Slack apps using the umbrella bot scope can't request additional scopes to adjust message authorship.

    For classic Slack apps, the best way to control the authorship of a message is to be explicit with the as_user parameter.

    If you don't use the as_user parameter, chat.postEphemeral will guess the most appropriate as_user interpretation based on the kind of token you're using.

    If as_user is not provided at all, then the value is inferred, based on the scopes granted to the caller: If the caller could post with as_user passed as false, then that is how the method behaves; otherwise, the method behaves as if as_user were passed as true.

    When as_user is false

    When the as_user parameter is set to false, messages are posted as "bot_messages", with message authorship attributed to the user name and icons associated with the Slack App.

    When as_user is true

    Set as_user to true and the authenticated user will appear as the author of the message. Posting as the authenticated user requires the client or the more preferred chat:write:user scopes.

    Target channels and users

    You must specify a conversation container (public channel, private channel, or an IM channel) by providing its ID to the channel argument. You also must specify a target user.

    Each type of channel behaves slightly differently based on the authenticated user's permissions and additional arguments. If the target user is not in the given channel, the ephemeral message will not be delivered, and we'll return a user_not_in_channel error.

    Workspace apps will receive a no_permission error when they are not a member of the specified channel.

    Note that the user parameter expects a user's id, and not a username or display name.

    Post to a public channel

    You can either pass the channel's name (#general) or encoded ID (C024BE91L), and the message will be posted to that channel. The channel's ID can be retrieved through the channels.list API method.

    Post to a private group

    As long as the authenticated user is a member of the private group, you can either pass the group's name (secret-group) or encoded ID (G012AC86C), and the message will be posted to that group. The private group's ID can be retrieved through the conversations.list API method.

    Post to an IM channel

    Posting to an IM channel is a little more complex depending on the value of as_user.

    • If as_user is false:
      • Pass a username (@chris) as the value of channel to post to that user's @slackbot channel as the bot.
      • Pass the IM channel's ID (D023BB3L2) as the value of channel to post to that IM channel as the bot. The IM channel's ID can be retrieved through the im.list API method.
    • If as_user is true:
      • Pass the IM channel's ID (D023BB3L2) as the value of channel to post to that IM channel as the authenticated user. The IM channel's ID can be retrieved through the im.list API method.

    To send a direct message to the user owning the token used in the request, provide the channel field with the a conversation/IM ID value found in a method like im.list.

    The message_ts included with the response cannot be used with chat.update, as it does not represent an actual message written to the database like it does with other api methods.

    Example responses

    Common successful response

    Typical success response

        "ok": true,
        "message_ts": "1502210682.580145"

    Common error response

    Typical error response

        "ok": false,
        "error": "user_not_in_channel"


    This table lists the expected errors that this method could return. However, other errors can be returned in the case where the service is down or other unexpected factors affect processing. Callers should always check the value of the ok params in the response.


    Value passed for channel was invalid.


    Blocks submitted with this message are not valid


    The blocks is not a valid JSON object or doesn't match the Block Kit syntax.


    Channel has been archived.


    Members on this team are sending too many messages. For more details, see


    Messages tab for the app is disabled.


    Message text is too long


    No message text provided


    A workspace preference prevents the authenticated user from posting.


    Too many attachments were provided with this message. A maximum of 100 attachments are allowed on a message.


    Intended recipient is not in the specified channel.


    Access to a resource specified in the request is denied.


    Authentication token is for a deleted user or workspace when using a bot token.


    The endpoint has been deprecated.


    Administrators have suspended the ability to post a message.


    The method cannot be called from an Enterprise.


    Some aspect of authentication cannot be validated. Either the provided token is invalid or the request originates from an IP address disallowed from making the request.


    The method has been deprecated.


    The token used is not granted the specific scope permissions required to complete this request.


    The token type used in this request is not allowed.


    No authentication token provided.


    The workspace token used in this request does not have the permissions necessary to complete the request. Make sure your app is a member of the conversation it's attempting to post a message to.


    The workspace is undergoing an enterprise migration and will not be available until migration is complete.


    Authentication token has expired


    Authentication token is for a deleted user or workspace or the app has been removed when using a user token.


    Two factor setup is required.


    The token used is not granted the specific workspace access required to complete this request.


    Access to this method is limited on the current network


    The server could not complete your operation(s) without encountering a catastrophic error. It's possible some aspect of the operation succeeded before the error was raised.


    The server could not complete your operation(s) without encountering an error, likely due to a transient issue on our end. It's possible some aspect of the operation succeeded before the error was raised.


    The method was passed an argument whose name falls outside the bounds of accepted or expected values. This includes very long names and names with non-alphanumeric characters other than _. If you get this error, it is typically an indication that you have made a very malformed API call.


    The method was either called with invalid arguments or some detail about the arguments passed is invalid, which is more likely when using complex arguments like blocks or attachments.


    The method was passed an array as an argument. Please only input valid strings.


    The method was called via a POST request, but the charset specified in the Content-Type header was invalid. Valid charset names are: utf-8 iso-8859-1.


    The method was called via a POST request with Content-Type application/x-www-form-urlencoded or multipart/form-data, but the form data was either missing or syntactically invalid.


    The method was called via a POST request, but the specified Content-Type was invalid. Valid types are: application/json application/x-www-form-urlencoded multipart/form-data text/plain.


    The method was called via a POST request and included a data payload, but the request did not include a Content-Type header.


    The request has been ratelimited. Refer to the Retry-After header for when to retry the request.


    The method was called via a POST request, but the POST data was either missing or truncated.


    The service is temporarily unavailable


    The workspace associated with your request is currently undergoing migration to an Enterprise Organization. Web API and other platform operations will be intermittently unavailable until the transition is complete.


    This table lists the expected warnings that this method will return. However, other warnings can be returned in the case where the service is experiencing unexpected trouble.


    The method was called via a POST request, and recommended practice for the specified Content-Type is to include a charset parameter. However, no charset was present. Specifically, non-form-data content types (e.g. text/plain) are the ones for which charset is recommended.


    The method was called via a POST request, and the specified Content-Type is not defined to understand the charset parameter. However, charset was in fact present. Specifically, form-data content types (e.g. multipart/form-data) are the ones for which charset is superfluous.


    Need a token? Create and install a Slack app to begin.
    This will make a real API request. Beware of using it with live workspaces.

    API response

    Submit your arguments to see the API response
    Calling chat.postEphemeral
    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; public class ChatPostEphemeral { 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.message("secret", (req, ctx) -> { var logger = ctx.logger; try { var event = req.getEvent(); // Call the chat.postEphemeral method using the built-in WebClient var result = ctx.client().chatPostEphemeral(r -> r // The token you used to initialize your app is stored in the `context` object .token(ctx.getBotToken()) // Payload message should be posted in the channel where original message was heard .channel(event.getChannel()) // The user the message should appear for .user(event.getUser()) .text("Shhhh only you can see this :shushing_face:") );"result: {}", result); } catch (IOException | SlackApiException e) { logger.error("error: {}", e.getMessage(), e); } return ctx.ack(); }); var server = new SlackAppServer(app); server.start(); } }
    Code to initialize Bolt app
    // Require the Node Slack SDK package ( 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 });
    // ID of the channel you want to send the message to const channelId = "C12345"; // ID of the user you want to show the ephemeral message to const userId = "U12345"; try { // Call the chat.postEphemeral method using the WebClient const result = await{ channel: channelId, user: userId, text: "Shhhh only you can see this :shushing_face:" }); console.log(result); } catch (error) { console.error(error); }