> ## Documentation Index > Fetch the complete documentation index at: https://docs.tightknit.ai/llms.txt > Use this file to discover all available pages before exploring further. # Create a Slack message > Posts to a channel, sends direct messages, or both. The message goes out immediately and cannot be unsent. A refusal carries one of these `code` values: - `invalid_blocks` (400): Slack or the Block Kit check rejected the blocks. - `no_recipients` (400): Neither `channel_id` nor `dm_slack_profile_ids` was given. - `too_many_dm_recipients` (400): More direct-message recipients than one request allows. - `channel_not_found` (422): The channel is not in the Slack workspace. - `not_in_channel` (422): The Tightknit app is not in the channel and could not join it. - `channel_not_allowed` (422): The channel is private and the Tightknit app is not in it, or it is archived, a direct message, or the Tightknit Hub. - `cannot_publish` (422): The channel's feed does not accept site posts. - `dm_delivery_failed` (422): No direct message could be delivered. - `no_workspace` (409): Slack is not connected to the community. - `no_community` (409): A `community` send, but the community has no name configured. - `missing_scope` (409): The Slack app lacks a permission the send needs; reconnect Slack. - `slack_unavailable` (503): Slack could not be reached; retry later. ## OpenAPI ````yaml /openapi-v1.json post /v1/slack_messages openapi: 3.1.0 info: title: Tightknit Admin API version: 1.0.0 description: Administrative access to a Tightknit community. servers: - url: https://api.tightknit.ai security: - Bearer: [] tags: - name: API keys description: Inspect the key a request authenticated with. - name: Awards description: Badges and certificates a community grants its members. - name: Events description: Read, create, update and delete events on the community calendar. - name: Journeys description: Read multi-step member programs and their milestones. - name: Tags description: The labels that classify events and content resources. - name: Groups description: The segments a community sorts its members into. - name: Content description: >- The collections a community files its content under, and the links and events in them. - name: Feeds description: The Slack channels and site-only spaces a community posts in. - name: Files description: Images and documents a community has uploaded. - name: Messages description: What a community has published. - name: Members description: The people in a community. - name: Slack messages description: >- Messages sent to Slack. Sending is the only operation: they cannot be read, edited or deleted here. - name: Compositions description: >- Message Blaster drafts: messages saved in Studio before, and kept after, they are sent to Slack channels and members. An API key sees only the compositions shared with every Studio user. - name: Follows description: What a member follows. - name: Polls description: The questions a community puts to its members in Slack. - name: Activity logs description: What members did in the community, and when. - name: System description: Service health. paths: /v1/slack_messages: post: tags: - Slack messages summary: Create a Slack message description: >- Posts to a channel, sends direct messages, or both. The message goes out immediately and cannot be unsent. A refusal carries one of these `code` values: - `invalid_blocks` (400): Slack or the Block Kit check rejected the blocks. - `no_recipients` (400): Neither `channel_id` nor `dm_slack_profile_ids` was given. - `too_many_dm_recipients` (400): More direct-message recipients than one request allows. - `channel_not_found` (422): The channel is not in the Slack workspace. - `not_in_channel` (422): The Tightknit app is not in the channel and could not join it. - `channel_not_allowed` (422): The channel is private and the Tightknit app is not in it, or it is archived, a direct message, or the Tightknit Hub. - `cannot_publish` (422): The channel's feed does not accept site posts. - `dm_delivery_failed` (422): No direct message could be delivered. - `no_workspace` (409): Slack is not connected to the community. - `no_community` (409): A `community` send, but the community has no name configured. - `missing_scope` (409): The Slack app lacks a permission the send needs; reconnect Slack. - `slack_unavailable` (503): Slack could not be reached; retry later. operationId: createSlackMessage requestBody: required: true content: application/json: schema: $ref: '#/components/schemas/SlackMessageCreate' responses: '200': description: Success headers: Request-Id: description: Identifier for this request, quote it in support tickets. schema: type: string content: application/json: schema: $ref: '#/components/schemas/SlackMessage' default: description: Error headers: Request-Id: description: Identifier for this request, quote it in support tickets. schema: type: string content: application/problem+json: schema: $ref: '#/components/schemas/Problem' security: - Bearer: [] components: schemas: SlackMessageCreate: type: object properties: channel_id: type: string pattern: ^[CG][A-Z0-9]{8,20}$ description: >- The channel to post in. A private channel must have the Tightknit app in it; the app joins a public channel it cannot otherwise post to. dm_slack_profile_ids: type: array items: type: string pattern: ^[UW][A-Z0-9]{8,20}$ minItems: 1 maxItems: 50 description: >- Members to also send the message to as a direct message from the app, one each. A profile's `slack_profile_id`. text: type: string minLength: 1 maxLength: 3000 description: >- The message as Slack `mrkdwn`, sent as a single section block. Send this or `blocks`. blocks: type: array items: type: object properties: type: type: string description: The Block Kit block type, such as `section`. required: - type additionalProperties: {} minItems: 1 maxItems: 50 description: >- The message as a Slack Block Kit payload, which Slack validates. Send this or `text`. identity: type: string enum: - community - bot default: community description: |- Who the channel message is posted as. One of: - `community`: the app under the community name and logo. - `bot`: the app itself. thread_ts: type: string pattern: ^\d{10}\.\d{6}$ description: Post as a reply in this message's thread, in the same channel. publish_to_site: type: boolean description: >- Also publish the channel message to the community site, when the channel's feed accepts posts. additionalProperties: false SlackMessage: type: object properties: object: type: string enum: - slack_message description: Always `slack_message`. channel_id: anyOf: - type: string - type: 'null' example: C01ABC123 description: >- Slack’s id for the channel the message was posted in. `null` when the message went out only as direct messages. ts: anyOf: - type: string - type: 'null' example: '1718000042.000123' description: >- The channel message's Slack timestamp. `null` when the message went out only as direct messages. message_id: anyOf: - type: string - type: 'null' example: msg_9f2b8c1d4e5a description: The community site post, when `publish_to_site` created one. failed_dm_slack_profile_ids: type: array items: type: string example: - U0BRY4S6LNQ description: >- Direct message recipients the message did not reach. The rest of the send went out, so sending again would repeat it. required: - object - channel_id - ts - message_id - failed_dm_slack_profile_ids Problem: type: object properties: type: type: string description: A URI naming the problem type. Always `about:blank`. example: about:blank title: type: string description: A short summary of the HTTP status. example: Not found status: type: integer description: The HTTP status code. example: 404 detail: type: string description: What went wrong with this request, when there is more to say. code: type: string description: >- A stable, machine-readable error code to branch on, unlike `title` and `detail`. example: not_found param: type: string description: The request field or parameter the error is about, when one is. request_id: type: string description: >- The id of the request, also sent as the `Request-Id` header. Quote it in support tickets. example: req_9f2b8c1d4e5a6b7c8d9e0f1a2b3c4d5e required: - type - title - status - code securitySchemes: Bearer: type: http scheme: bearer bearerFormat: Tightknit API key description: 'A Tightknit admin API key, sent as `Authorization: Bearer `.' ```` ## Related topics - [Create Channels and Feeds](https://docs.tightknit.ai/guides/create-your-core-channels.md) - [Create Your Slack Workspace](https://docs.tightknit.ai/guides/create-your-slack-workspace.md) - [Message Blaster](https://docs.tightknit.ai/studio/message-blaster.md) - [Create a milestone Slack channel](https://docs.tightknit.ai/v1/api-reference/journeys/create-a-milestone-slack-channel.md) - [Slack Sync Guide](https://docs.tightknit.ai/slack/sync-guide.md) This documentation is built and hosted on [Mintlify](https://mintlify.com), a developer documentation platform.