How to Send Asana Milestone Updates to Slack with n8n

n8n Dashboard > Workflows > + New Workflow

Create a new n8n workflow

Open your n8n instance and click the '+ New Workflow' button in the top-left of the Workflows dashboard. Give it a clear name like 'Asana Milestones → Slack'. You'll land on a blank canvas with a single 'Add first step' node in the center. This is where you'll drop the trigger.

1. 1Click '+ New Workflow' in the top-left corner
2. 2Click the pencil icon next to 'My workflow' and rename it 'Asana Milestones → Slack'
3. 3Click the large '+ Add first step' node on the canvas

Canvas > Add first step > Search 'Schedule' > Schedule Trigger

Add the Schedule trigger

In the node search panel, type 'Schedule' and select 'Schedule Trigger'. Set the interval to 'Every 5 Minutes'. This is your polling clock — every 5 minutes n8n will run the rest of the workflow to check Asana for changes. Asana's REST API does not push events to n8n without a publicly reachable webhook endpoint, so polling is the practical default for most self-hosted setups.

1. 1Type 'Schedule' in the node search box
2. 2Click 'Schedule Trigger' from the results
3. 3Set 'Trigger Interval' to 'Minutes'
4. 4Set 'Minutes Between Triggers' to 5
5. 5Click 'Save' in the top-right

Canvas > + > Asana > Credentials > Create New > Personal Access Token

Connect your Asana account

Click the '+' button after the Schedule Trigger to add a new node. Search for 'Asana' and select it. Click 'Create New Credential' in the node panel. You'll be prompted to choose between OAuth2 and Personal Access Token — use Personal Access Token for self-hosted n8n unless you have a public callback URL configured for OAuth. Copy your Asana PAT from Asana > My Profile Settings > Apps > Manage Developer Apps.

1. 1Click the '+' connector after the Schedule Trigger node
2. 2Search 'Asana' and select the Asana node
3. 3In the node panel, click the 'Credential for Asana API' dropdown
4. 4Click 'Create New Credential'
5. 5Paste your Asana Personal Access Token and click 'Save'

Asana Node > Resource: Task > Operation: Get Many > Filters

Configure the Asana node to fetch tasks

In the Asana node, set Resource to 'Task' and Operation to 'Get Many'. Set 'Return All' to true only if your projects have fewer than 500 tasks — above that, enable pagination manually. Under Filters, add 'Project' and enter your Asana project GID (found in the URL of the project: app.asana.com/0/PROJECT_GID/list). Add a second filter: 'Completed Since' set to a dynamic expression that looks back 6 minutes so you catch anything completed since the last poll.

1. 1Set 'Resource' to 'Task'
2. 2Set 'Operation' to 'Get Many'
3. 3Toggle 'Return All' to true
4. 4Under 'Additional Fields', click 'Add Field' and select 'Project'
5. 5Enter your Asana project GID in the Project field
6. 6Click 'Add Field' again and select 'Completed Since', then enter the expression: {{ new Date(Date.now() - 6 * 60 * 1000).toISOString() }}

Canvas > + after Asana node > Filter

Filter for milestone tasks only

Asana milestones are tasks where 'resource_subtype' equals 'milestone'. Add a Filter node after the Asana node to keep only those records. Without this filter, every completed task — subtasks, regular tasks, all of them — will post to Slack, which gets noisy fast. You can also add a second condition here for deadline proximity if you want 'approaching deadline' alerts alongside completion alerts.

1. 1Click '+' after the Asana node and search 'Filter'
2. 2Select 'Filter' from the list
3. 3Click 'Add Condition'
4. 4Set Field to {{ $json.resource_subtype }}
5. 5Set Condition to 'equals'
6. 6Set Value to 'milestone'
7. 7Click 'Add Condition' again, set Field to {{ $json.completed }}, Condition to 'equals', Value to true

Canvas > + parallel from Asana node > Filter > Merge node

Add a deadline proximity branch

To also catch milestones with deadlines approaching in the next 48 hours, add an 'OR' branch to your filter — or add a second Filter node connected in parallel from the Asana node. Set the condition to check if 'due_on' is within 2 days of today. Use the expression: {{ Math.ceil((new Date($json.due_on) - new Date()) / (1000 * 60 * 60 * 24)) }} and check if it is less than or equal to 2. Merge both branches with a Merge node before the Slack step.

1. 1Click the '+' on the Asana node again to add a second parallel path
2. 2Add a second Filter node
3. 3Set condition: {{ $json.resource_subtype }} equals 'milestone'
4. 4Add condition: {{ $json.completed }} equals false
5. 5Add condition: {{ Math.ceil((new Date($json.due_on) - new Date()) / (1000*60*60*24)) }} less than or equal to 2
6. 6Add a 'Merge' node after both Filter nodes and connect both branches to it

Canvas > + after Merge node > Code

Add a Code node to format the Slack message

Add a Code node after the Merge node. This is where you construct the Slack Block Kit message payload. You have access to all Asana task fields here: name, due_on, assignee, completed status, and the project name from the memberships array. The Code node runs once per item, so each milestone gets its own formatted message. Paste the code from the pro tip section below.

1. 1Click '+' after the Merge node and search 'Code'
2. 2Select the 'Code' node
3. 3Set 'Mode' to 'Run Once For Each Item'
4. 4Paste the JavaScript from the pro tip section into the code editor
5. 5Click 'Test Step' to verify the output contains a formatted 'blocks' array

Paste this into the Code node in Step 7. Set Mode to 'Run Once For Each Item'. It builds the full Slack Block Kit payload, resolves the correct Slack channel from a project-to-channel map, handles null assignees, formats dates, and flags whether this is a completion alert or a deadline warning — so your Slack messages are immediately readable without any extra config.

// n8n Code Node — Run Once For Each Item
// Maps Asana milestone data to a formatted Slack Block Kit message
const task = $input.item.json;

// n8n Code Node — Run Once For Each Item
// Maps Asana milestone data to a formatted Slack Block Kit message

const task = $input.item.json;

// Map Asana project GIDs to Slack channel IDs
// Update these with your actual project GIDs and channel IDs
const PROJECT_CHANNEL_MAP = {
  '1199000000001234': 'C045ABCDE12',  // Q1 Product Launch → #product-updates
  '1199000000005678': 'C067FGHIJ34',  // Platform Reliability → #eng-reliability
  'default': 'C089KLMNO56'             // #general-updates fallback
};

// Resolve project info from memberships array
const membership = task.memberships && task.memberships.length > 0
  ? task.memberships[0]
  : null;
const projectName = membership?.project?.name || 'Unknown Project';
const projectGid = membership?.project?.gid || 'default';

// Resolve Slack channel
const channel = PROJECT_CHANNEL_MAP[projectGid] || PROJECT_CHANNEL_MAP['default'];

// Resolve assignee safely
const assigneeName = task.assignee?.name || 'Unassigned';

// Format dates
const formatDate = (dateStr) => {
  if (!dateStr) return 'No date set';
  const d = new Date(dateStr);
  return d.toLocaleDateString('en-US', { month: 'short', day: 'numeric', year: 'numeric' });
};

// Calculate days until due
const daysUntilDue = task.due_on
  ? Math.ceil((new Date(task.due_on) - new Date()) / (1000 * 60 * 60 * 24))
  : null;

// Determine alert type
const isComplete = task.completed === true;
const headerText = isComplete ? '✅ Milestone Complete' : `⚠️ Milestone Due in ${daysUntilDue} Day${daysUntilDue === 1 ? '' : 's'}`;
const dateLabel = isComplete
  ? `📅 Completed: ${formatDate(task.completed_at)}`
  : `📅 Due: ${formatDate(task.due_on)}`;

// Build Block Kit blocks array
const blocks = [
  {
    type: 'header',
    text: { type: 'plain_text', text: headerText, emoji: true }
  },
  {
    type: 'section',
    text: {
      type: 'mrkdwn',
      text: `*${task.name}*\n📁 Project: ${projectName}\n👤 Owner: ${assigneeName}\n${dateLabel}`
    }
  }
];

// Add notes if present (truncate to 200 chars)
if (task.notes && task.notes.trim().length > 0) {
  const truncatedNotes = task.notes.length > 200
    ? task.notes.substring(0, 197) + '...'
    : task.notes;
  blocks.push({
    type: 'section',
    text: { type: 'mrkdwn', text: truncatedNotes }
  });
}

// Add divider
blocks.push({ type: 'divider' });

return { channel, blocks, taskGid: task.gid, projectName, isComplete };

Canvas > + after Code node > Slack > Credentials > Create New > OAuth2

Connect your Slack account

Add a Slack node after the Code node. Click 'Create New Credential' and choose OAuth2. You'll need to create a Slack App at api.slack.com/apps with the scopes: chat:write, channels:read, and groups:read. Once your app is installed to your workspace, copy the Bot OAuth Token and paste it into n8n. The bot must be manually invited to any private channel you want to post to.

1. 1Click '+' after the Code node and search 'Slack'
2. 2Select the Slack node
3. 3Click 'Credential for Slack API' dropdown and select 'Create New Credential'
4. 4Paste your Slack Bot OAuth Token (starts with xoxb-)
5. 5Click 'Save'

Slack Node > Resource: Message > Operation: Post

Configure the Slack message action

In the Slack node, set Resource to 'Message' and Operation to 'Post'. For 'Channel', use the expression {{ $json.channel }} to pull the channel ID from your Code node output. Set 'Message Type' to 'Block'. In the 'Blocks' field, reference {{ $json.blocks }} from the Code node. This sends the fully formatted Block Kit message, including bold project name, milestone title, assignee, and due date.

1. 1Set 'Resource' to 'Message'
2. 2Set 'Operation' to 'Post'
3. 3Set 'Channel' to expression mode and enter {{ $json.channel }}
4. 4Set 'Message Type' to 'Block'
5. 5Set 'Blocks' to expression mode and enter {{ JSON.stringify($json.blocks) }}

Canvas > + after Schedule Trigger > Code (before Asana node)

Add deduplication with n8n static data

Without deduplication, every poll will re-fetch and re-post any milestone that was completed in the last 6 minutes AND is still within the polling overlap window. Add a Code node before your Filter nodes. Use n8n's built-in static workflow data to store GIDs of milestones already posted. On each run, skip any GID already in that store and add new ones after posting.

1. 1Click '+' after the Schedule Trigger to insert a Code node before the Asana node
2. 2Set Mode to 'Run Once For All Items'
3. 3Paste the deduplication initialization code (see pro tip)
4. 4After the Slack node, add another Code node to write the posted GID to static data
5. 5Connect this final Code node back to nothing — it's a terminal write step

Canvas > Activate toggle (top right) > Left sidebar > Executions

Activate the workflow and verify

Click the toggle in the top-right of the canvas to activate the workflow. n8n will immediately begin polling on your 5-minute schedule. Watch the 'Executions' tab in the left sidebar — you should see a new execution entry every 5 minutes. Click any execution to inspect what data came through each node. Run a test by marking an Asana milestone complete and waiting up to 5 minutes for the Slack message to appear.

1. 1Click the grey toggle switch in the top-right corner of the canvas
2. 2Confirm the toggle turns green and shows 'Active'
3. 3Click 'Executions' in the left sidebar
4. 4Mark a test Asana milestone complete
5. 5Wait 5 minutes and confirm the Slack message appears in the target channel