Slack

output.slack Output v0.1.0

Sends a Slack message (text or Block Kit blocks) to a channel via chat.postMessage with a bot token. Leave the text blank to send the input payload as pretty-printed JSON.

The Slack step on the Studio canvas — The **Slack** step as it appears on the Studio canvas — input pins on the left, output ports on the right.

Finding it in the library

Search the builder's node library for Slack (it lives under Output). A single click opens the in-editor docs panel shown here — description, ports, and every property, without leaving the canvas. Double-click (or drag) to add it to the workflow.

Slack in the node library, with the in-editor docs panel open — The library entry and the in-editor docs panel for **Slack** — the same reference this page is generated from.

Wired up in the builder

Slack in a real, runnable flow — captured live from the Studio editor, exactly as it looks on your canvas. This is the same workflow used for the example input & output below.

Slack wired into a runnable workflow in the Studio builder — **Slack** wired into a runnable flow — input on the left, output on the right.

How it’s configured

The node’s Configure panel as it opens in the builder when you select the step — every setting laid out with real values. Click any field to edit it.

The Slack node's Configure panel in the Studio builder — The **Configure** panel for **Slack**, showing the settings from the flow above.

Ports

Ports are the node’s contract with its neighbours. In the editor a port label renders bold when wired and italic when optional; ◈ ports accept attachment carriers rather than data wires.

Direction	Port	Label	What flows through it
Input	`input`	Input
Output	`output`	Send result

How data flows through it

Slack consumes the content of the incoming envelope — when it is fed directly by a trigger, the trigger’s wrapper is unwrapped at the node boundary so the node sees the actual data, not the metadata shell. Its output becomes the payload for the next node, while the envelope (trace ids, correlation, binary refs) rides along untouched. In the Runs view you always see the whole envelope for both sides of this node.

Expressions in the config

String-typed properties accept {{ }} expressions evaluated against the incoming item at run time — e.g. {{ $json.customer.email }}. On this node that’s token, channel, text, baseUrl. JSON- and code-typed fields never interpolate — they are passed through literally.

Build it with AI

Every node in this reference is reachable through Flowdrome’s AI Copilot and the MCP tools — say what you want, and the graph surgery happens server-side. Node types resolve fuzzily, so the catalog label (Slack) works as well as the exact type id (output.slack).

In the Copilot panel (or any connected AI):

add a slack node after the trigger

As a step in a create_chain_workflow call:

{"type":"Slack","config":{}}

Raw MCP call — add this node to a workflow with add_node

curl -s -X POST http://localhost:48170/mcp -H "content-type: application/json" -d '{ "jsonrpc": "2.0", "id": "1", "method": "tools/call", "params": { "name": "add_node", "arguments": { "workflowId": "<id>", "type": "Slack" } } }'

Example input & output

Captured from a real test run of the workflow above — this is what you see in the run data panel after pressing Test workflow.

Input — what the node received

The Slack node's input envelope in the run data viewer — The input envelope in the Runs view — Flowdrome always shows the whole envelope, with the payload inside `body`.

Output — what the node produced

The Slack node's output envelope in the run data viewer — The output envelope after the step ran.

Property reference

Every setting, with its type and default — the same fields shown configured in the panel above.

Property	Type	Default	Description
Credential `credentialId`	`credential`	`""`	Use a stored credential for this connection — its fields are filled in at run start. Pick "None" to enter the connection details manually. accepts credential templates: `slack-bot`
Bot token `token`	`string`	`""`	Slack bot token — use ${credential.slack-bot.botToken}. Empty is allowed here; it must resolve by run time.
Channel `channel`	`string`	`""`	Channel ID (C…) or #name to post into.
Message `messageMode`	`select`	`"text"`	Plain text, or Block Kit blocks. `blockstext`
Text `text`	`string`	`""`	Message text. Leave blank to send the input payload as pretty-printed JSON. Shown when `(messageMode ?? "text") === "text"`
Blocks `blocks`	`json`	`[]`	Block Kit blocks as a JSON array. Shown when `messageMode === "blocks"`
Thread ts field `threadTsField`	`field`	`""`	Dot-path to a thread timestamp on the input — when set, the message is posted as a thread reply.
Base URL `baseUrl`	`string`	`"https://slack.com/api"`	Slack API base URL (override for testing).
Timeout (ms) `timeoutMs`	`int`	`15000`	Abort the request after this many milliseconds.

Related nodes

The rest of the Output group — the same folder you’d scan in the editor’s library.

This page is generated from the node registry by gen-node-docs.mjs on every site build — ports, properties, defaults and visibility rules cannot drift from the code. The screenshots and example data are captured from a live Flowdrome by npm run shots:nodes and npm run gen:examples.