How to Assign Todoist Tasks from Slack Mentions with n8n

api.slack.com/apps > Create New App > Event Subscriptions

Create a Slack App and Enable Event Subscriptions

Go to api.slack.com/apps and click 'Create New App', then choose 'From scratch'. Name it something like 'n8n Task Bot' and select your workspace. You need this custom app to receive mention events via webhook — n8n's built-in Slack OAuth credential does not expose event subscriptions without a custom app. Once created, go to 'Event Subscriptions' in the left sidebar and toggle it on.

1. 1Go to api.slack.com/apps and click 'Create New App'
2. 2Select 'From scratch', enter app name, choose your workspace
3. 3Click 'Event Subscriptions' in the left sidebar
4. 4Toggle 'Enable Events' to On — leave the Request URL blank for now

This single Code node handles three things at once: extracts the mentioned user ID from Slack's bracket syntax, strips the bot mention from the task content so it reads cleanly, detects urgency keywords to set Todoist priority, and constructs the Slack message deep link. Paste this into the first Code node (Step 6) — it expects the raw Slack webhook body at $input.first().json.body.

// n8n Code Node — Parse Slack Mention and Prepare Todoist Fields
// Paste into the Code node (Step 6). Language: JavaScript.
const event = $input.first().json.body.event;

// n8n Code Node — Parse Slack Mention and Prepare Todoist Fields
// Paste into the Code node (Step 6). Language: JavaScript.

const event = $input.first().json.body.event;

// Extract all user mentions from the message text
// Slack format: <@U012AB3CD> for user mentions
const mentionRegex = /<@(U[A-Z0-9]+)>/g;
const allMentions = [...event.text.matchAll(mentionRegex)].map(m => m[1]);

// The bot's own user ID — set this from your Slack App config (Bot User ID)
// Found at: api.slack.com/apps > [App] > App Home > App ID section
const BOT_USER_ID = process.env.SLACK_BOT_USER_ID || 'UBOTID000';

// The first mention that is NOT the bot is the intended assignee
const mentionedUserId = allMentions.find(id => id !== BOT_USER_ID) || null;

if (!mentionedUserId) {
  throw new Error('No non-bot user mention found in message. Skipping task creation.');
}

// Clean the message text: remove all <@USERID> patterns and trim whitespace
const cleanedText = event.text
  .replace(/<@[A-Z0-9]+>/g, '')
  .replace(/\s+/g, ' ')
  .trim();

// Detect urgency keywords to set Todoist priority
// Todoist priority: 1 = normal, 2 = medium, 3 = high, 4 = urgent
const urgentKeywords = ['urgent', 'asap', 'immediately', 'critical', 'blocker'];
const highKeywords = ['today', 'eod', 'end of day', 'by noon'];
const lowerText = cleanedText.toLowerCase();

let priority = 1;
if (urgentKeywords.some(kw => lowerText.includes(kw))) {
  priority = 4;
} else if (highKeywords.some(kw => lowerText.includes(kw))) {
  priority = 3;
}

// Construct Slack deep link to original message
// Format: https://workspace.slack.com/archives/CHANNELID/pTIMESTAMP
// The ts field uses a dot (e.g. 1710234567.000100) — deep link uses p + digits without dot
const tsForLink = event.ts.replace('.', '');
const SLACK_WORKSPACE_DOMAIN = process.env.SLACK_WORKSPACE_DOMAIN || 'yourworkspace';
const slackMessageLink = `https://${SLACK_WORKSPACE_DOMAIN}.slack.com/archives/${event.channel}/p${tsForLink}`;

return [
  {
    json: {
      mentionedUserId,
      channelId: event.channel,
      messageText: cleanedText,
      priority,
      slackMessageLink,
      originalTs: event.ts,
      triggeredByUserId: event.user
    }
  }
];

n8n Canvas > + Add Node > Trigger > Webhook

Create the n8n Webhook Node

Open n8n and create a new workflow. Add a 'Webhook' node as the first node — this is under the 'Trigger' section in the node panel. Set the HTTP Method to POST and leave the path as the auto-generated value. Copy the 'Test URL' shown in the node — you'll paste this into Slack's Event Subscriptions page. Keep this node open in test mode so Slack can verify the endpoint.

1. 1Click the '+' button on the blank canvas
2. 2Search for 'Webhook' and select it under Trigger nodes
3. 3Set HTTP Method to 'POST'
4. 4Click 'Listen for Test Event' to activate the test listener
5. 5Copy the full Test URL from the node panel

api.slack.com/apps > [Your App] > Event Subscriptions > Subscribe to Bot Events

Paste the Webhook URL into Slack and Subscribe to Events

Go back to the Slack app config page and paste the n8n webhook Test URL into the 'Request URL' field under Event Subscriptions. Slack will immediately send a challenge request to verify the endpoint. n8n will automatically respond to this challenge — you'll see it captured in the Webhook node in n8n. Once Slack shows a green 'Verified' checkmark, scroll down to 'Subscribe to bot events' and add the event you need.

1. 1Paste the n8n Test URL into the 'Request URL' field
2. 2Wait for the green 'Verified' badge to appear next to the URL
3. 3Scroll to 'Subscribe to bot events' and click 'Add Bot User Event'
4. 4Search for and select 'app_mention'
5. 5Click 'Save Changes' at the bottom of the page

api.slack.com/apps > [Your App] > OAuth & Permissions > Scopes

Set OAuth Scopes and Install the App

Go to 'OAuth & Permissions' in the left sidebar of your Slack app config. Under 'Bot Token Scopes', add the required scopes. Then scroll up and click 'Install to Workspace'. After approval, copy the 'Bot User OAuth Token' — it starts with xoxb-. You'll add this to n8n's Slack credential.

1. 1Click 'OAuth & Permissions' in the left sidebar
2. 2Under 'Bot Token Scopes', click 'Add an OAuth Scope'
3. 3Add: app_mentions:read, channels:history, users:read
4. 4Click 'Install to Workspace' at the top of the page
5. 5Approve the permissions and copy the 'Bot User OAuth Token'

n8n > Credentials > New > Slack API

Add Slack Credential to n8n and Invite Bot to Channels

In n8n, go to Credentials in the left sidebar and create a new 'Slack API' credential. Paste the xoxb- token into the 'Access Token' field and save. Back in Slack, go to each project channel you want to monitor and type /invite @YourBotName to add the bot. The bot must be a member of a channel to receive app_mention events from it.

1. 1In n8n, click 'Credentials' in the left sidebar
2. 2Click '+ Add Credential' and search for 'Slack API'
3. 3Paste the xoxb- Bot Token into the 'Access Token' field
4. 4Click 'Save' and confirm the green checkmark appears
5. 5In each target Slack channel, type /invite @YourBotName and press Enter

n8n Canvas > + Add Node > Core > Code

Parse the Mention and Extract the Tagged User

Add a 'Code' node after the Webhook node. The raw Slack event payload contains the message text with user mentions in the format <@U012AB3CD>. You need to extract the mentioned user's Slack ID from this string and map it to a Todoist assignee. This Code node will also extract the channel ID so you can route to the right Todoist project. Paste the JavaScript from the Pro Tip section below into this node.

1. 1Click '+' after the Webhook node to add a new node
2. 2Search for 'Code' and select it
3. 3Set Language to 'JavaScript'
4. 4Paste the code from the Pro Tip section into the code editor
5. 5Click 'Test Step' to verify it parses a sample Slack payload

n8n Canvas > + Add Node > Core > HTTP Request

Resolve Slack User ID to Email with Slack HTTP Node

Add an 'HTTP Request' node to call the Slack users.info API. This converts the Slack user ID you extracted in Step 6 into an email address, which is what Todoist needs to assign a task. The endpoint is https://slack.com/api/users.info and requires the user ID as a query parameter. Use the xoxb- token as a Bearer token in the Authorization header.

1. 1Add an 'HTTP Request' node after the Code node
2. 2Set Method to 'GET'
3. 3Set URL to 'https://slack.com/api/users.info'
4. 4Under Query Parameters, add 'user' = '{{ $json.mentionedUserId }}'
5. 5Under Headers, add 'Authorization' = 'Bearer xoxb-your-token-here'

This single Code node handles three things at once: extracts the mentioned user ID from Slack's bracket syntax, strips the bot mention from the task content so it reads cleanly, detects urgency keywords to set Todoist priority, and constructs the Slack message deep link. Paste this into the first Code node (Step 6) — it expects the raw Slack webhook body at $input.first().json.body.

// n8n Code Node — Parse Slack Mention and Prepare Todoist Fields
// Paste into the Code node (Step 6). Language: JavaScript.
const event = $input.first().json.body.event;

// n8n Code Node — Parse Slack Mention and Prepare Todoist Fields
// Paste into the Code node (Step 6). Language: JavaScript.

const event = $input.first().json.body.event;

// Extract all user mentions from the message text
// Slack format: <@U012AB3CD> for user mentions
const mentionRegex = /<@(U[A-Z0-9]+)>/g;
const allMentions = [...event.text.matchAll(mentionRegex)].map(m => m[1]);

// The bot's own user ID — set this from your Slack App config (Bot User ID)
// Found at: api.slack.com/apps > [App] > App Home > App ID section
const BOT_USER_ID = process.env.SLACK_BOT_USER_ID || 'UBOTID000';

// The first mention that is NOT the bot is the intended assignee
const mentionedUserId = allMentions.find(id => id !== BOT_USER_ID) || null;

if (!mentionedUserId) {
  throw new Error('No non-bot user mention found in message. Skipping task creation.');
}

// Clean the message text: remove all <@USERID> patterns and trim whitespace
const cleanedText = event.text
  .replace(/<@[A-Z0-9]+>/g, '')
  .replace(/\s+/g, ' ')
  .trim();

// Detect urgency keywords to set Todoist priority
// Todoist priority: 1 = normal, 2 = medium, 3 = high, 4 = urgent
const urgentKeywords = ['urgent', 'asap', 'immediately', 'critical', 'blocker'];
const highKeywords = ['today', 'eod', 'end of day', 'by noon'];
const lowerText = cleanedText.toLowerCase();

let priority = 1;
if (urgentKeywords.some(kw => lowerText.includes(kw))) {
  priority = 4;
} else if (highKeywords.some(kw => lowerText.includes(kw))) {
  priority = 3;
}

// Construct Slack deep link to original message
// Format: https://workspace.slack.com/archives/CHANNELID/pTIMESTAMP
// The ts field uses a dot (e.g. 1710234567.000100) — deep link uses p + digits without dot
const tsForLink = event.ts.replace('.', '');
const SLACK_WORKSPACE_DOMAIN = process.env.SLACK_WORKSPACE_DOMAIN || 'yourworkspace';
const slackMessageLink = `https://${SLACK_WORKSPACE_DOMAIN}.slack.com/archives/${event.channel}/p${tsForLink}`;

return [
  {
    json: {
      mentionedUserId,
      channelId: event.channel,
      messageText: cleanedText,
      priority,
      slackMessageLink,
      originalTs: event.ts,
      triggeredByUserId: event.user
    }
  }
];

n8n Canvas > + Add Node > Core > Code

Map Channel ID to Todoist Project ID

Add another 'Code' node to map the Slack channel ID to a Todoist project ID. You'll hardcode this mapping as a JavaScript object — each Slack channel ID maps to one Todoist project ID. Get your Todoist project IDs from the Todoist API at todoist.com/API/v9/projects using your API token. This is a deliberate design choice: it keeps the routing logic explicit and editable without touching the workflow structure.

1. 1Add a second 'Code' node after the HTTP Request node
2. 2Paste the channel-to-project mapping object (see Pro Tip code)
3. 3Add your actual Slack channel IDs as keys and Todoist project IDs as values
4. 4Add a fallback project ID for channels not in the map
5. 5Click 'Test Step' to confirm the correct project ID is returned

n8n Canvas > + Add Node > Todoist > Create Task

Create the Todoist Task

Add a 'Todoist' node and select the 'Create Task' operation. Connect it using your Todoist API credential (create this under n8n Credentials using your Todoist API token from todoist.com/app/settings/integrations/developer). Map the task content, project ID, assignee email, and due date. The assignee email from Step 7 goes into the 'Assignee' field — Todoist will match it to a project collaborator.

1. 1Add a 'Todoist' node after the second Code node
2. 2Select 'Create Task' as the operation
3. 3Set 'Project ID' to '{{ $json.todoistProjectId }}'
4. 4Set 'Content' to the message text extracted in Step 6
5. 5Set 'Assignee' to the email from the HTTP Request node: '{{ $node["HTTP Request"].json.user.profile.email }}'

n8n Canvas > + Add Node > Core > IF

Add a Filter to Ignore Bot Messages and Non-Target Channels

Add an 'IF' node between the Webhook node and the Code parser. This prevents the workflow from creating tasks when the bot itself posts a message (which would cause a loop) and limits execution to only your configured channels. Check that the event subtype is not 'bot_message' and that the channel ID exists in your allowed list. Without this filter, any app_mention anywhere in the workspace will trigger task creation.

1. 1Add an 'IF' node directly after the Webhook node
2. 2Add Condition 1: '{{ $json.body.event.subtype }}' is not equal to 'bot_message'
3. 3Add Condition 2: '{{ $json.body.event.channel }}' contains one of your target channel IDs
4. 4Set the combinator to 'AND'
5. 5Connect the 'true' output to the Code parser node; leave the 'false' output unconnected

n8n Canvas > Webhook Node > Production URL | api.slack.com/apps > Event Subscriptions

Switch to Production URL and Activate Workflow

Go back to the Webhook node and copy the Production URL (not the Test URL). Update the Request URL in your Slack app's Event Subscriptions page to this Production URL. Slack will re-verify it — your active workflow will respond to the challenge automatically. Then click 'Activate' in the top-right of the n8n canvas to turn the workflow on.

1. 1Click the Webhook node and copy the Production URL
2. 2Go to api.slack.com/apps > your app > Event Subscriptions
3. 3Replace the Test URL with the Production URL and wait for 'Verified'
4. 4Return to n8n and click the 'Activate' toggle in the top-right corner
5. 5Confirm the workflow status shows 'Active' in green