Message Slack User

Send the given message to the specified user on execution. No input table needs to be specified, if one is given it is passed through verbatim.

Users should ideally be identified by their unique ID which looks something like 'U011N55HKCL', these IDs can be fetched with the Get Users node. It is however possible to provide the display name in the same way you would identify a user when messaging in the slack app, for example @Person for the user with the display name of 'Person' - the @ must be included to indicate it's a display name and not an ID. Display names are not unique and if multiple users with the same display name are found the node will fail. Please note by providing display names an API call to users.list will be made to enable lookup of the user's unique ID which is a 'Web API Tier 2' method.

To message a group of users the channels:manage scope must be set. Multiple users should be specified as a comma separated list such as U011N55HKCL,U011XEN1RDW. It is possible to mix and match display names and user IDs such as: @Person,U011XEN1RDW. White space will be automatically trimmed.

API call details: https://api.slack.com/methods/conversations.open and https://api.slack.com/methods/chat.postMessage

Notes on username: By default the message will be sent and display with the apps name. If the chat:write:customize scope has been added then it is possible to set a username parameter. If changing the display name / username of the source of the message is desirable then check 'Set username' and provide the username to post the message as. The messages will however appear undo the app regardless of what username is set.

Rate Limiting: The underlying Java Slack API offers an async approach where it attempts to manage Rate Limits on API requests. This node node uses the aysnc version of the method and will send approximately 1 message per second.

Options

Bot OAuth token: The OAth token of the bot to post as
User ID(s): The user to post to. To send to multiple users provide a comma seperated list of user IDs or display names. This value can be found in the ID column of the output table of the Get Users node.
Message: The message to post
Fail on error: Node will fail terminating workflow branch if checked. Uncheck to continue workflow if message can't be sent
Set username: Whether to use the custom provided username instead of bot name.
Username: A custom username to set, this will overide the default bot name. Ignored if Set username is not checked.

Input Ports

: Any input data table.

Output Ports

: The verbatim input table or an empty table if no input provided.

Popular Predecessors

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Popular Successors

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Installation

To use this node in KNIME, install the extension Slack integration from the below update site following our NodePit Product and Node Installation Guide:

v5.12

Plugin provider: Samuel Webb

Plugin version: 3.1.0.v202512021300

On NodePit since: 2026-07-06

Last update: 2026-07-12

KNIME versions: Since v4.1

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