How to Broadcast Trello Updates to Slack with n8n

Workflows > + Create > New Workflow

Create new n8n workflow

Log into your n8n instance and create a fresh workflow. You'll see the blank canvas with a Start node already placed. This workflow will listen for Trello webhooks and format messages for Slack. Click the Start node to begin configuration.

1. 1Click the purple + Create button
2. 2Select 'New Workflow' from the dropdown
3. 3Name it 'Trello to Slack Broadcaster'
4. 4Click the Start node to configure

Node > Delete > Add Node > Trello Trigger

Replace Start with Trello Webhook

Delete the Start node and add a Trello Trigger node. This creates a webhook endpoint that Trello will ping whenever cards change. Select 'Card Updated' as the trigger event since this covers both list moves and comments. The webhook URL will generate automatically.

1. 1Delete the Start node using the trash icon
2. 2Click the + button to add a node
3. 3Search for 'Trello Trigger' and select it
4. 4Choose 'Card Updated' from the Event dropdown

Trello Trigger > Credential > Create New

Connect Trello account

Click the Credential dropdown and create a new Trello connection. You'll need to authorize n8n to access your Trello boards. This requires your Trello API key and token, which you can get from the Trello developer portal. The connection stays active across all your Trello nodes.

1. 1Click 'Create New' next to Credential
2. 2Select 'Trello API' as credential type
3. 3Visit trello.com/app-key to get your API key
4. 4Generate a token and paste both values
5. 5Test the connection and save

Trello Trigger > Board > Select Board

Configure board and webhook

Select the Trello board you want to monitor from the Board dropdown. Copy the webhook URL from the node details. You'll register this URL with Trello in the next step. The webhook will fire for any card changes on this specific board only.

1. 1Select your target board from the Board dropdown
2. 2Copy the webhook URL from the 'Webhook URLs' section
3. 3Leave other settings at default
4. 4Save the node configuration

External API > Trello Webhooks > POST /webhooks

Register webhook with Trello

Use Trello's webhook API to register your n8n endpoint. Make a POST request to Trello's webhook endpoint with your board ID and n8n webhook URL. You can do this via Postman, curl, or Trello's API explorer. The webhook starts working immediately after registration.

1. 1Get your board ID from the Trello board URL
2. 2Make a POST to https://api.trello.com/1/webhooks
3. 3Include callbackURL (your n8n URL), idModel (board ID), and credentials
4. 4Verify you get a 200 response with webhook details

Add Node > Slack > Send Message

Add Slack node

Connect a Slack node to send messages when Trello cards update. Choose 'Send Message' as the operation. You'll configure the channel and message content in the following steps. The Slack node can post to any channel your bot has access to.

1. 1Click the + button after the Trello Trigger
2. 2Search for and select 'Slack'
3. 3Choose 'Send Message' from the Operation dropdown
4. 4Connect it to the Trello Trigger output

Slack > Credential > Create New > OAuth2

Connect Slack workspace

Create a new Slack credential using OAuth2. This opens a popup to authorize n8n access to your Slack workspace. Choose a bot token with channels:write and chat:write permissions. The connection lets you post messages to any public channel or private channels where the bot is added.

1. 1Click 'Create New' next to Credential
2. 2Select 'Slack OAuth2 API' credential type
3. 3Click 'Connect my account' to start OAuth flow
4. 4Authorize n8n in the Slack popup
5. 5Confirm the green connection success message

Slack > Channel > Text

Configure message content

Set up the Slack message template using Trello webhook data. Reference card name, list changes, and member actions from the Trello payload. Use expressions to format the message with card links and action details. The message should clearly explain what happened and who did it.

1. 1Select your target Slack channel from the dropdown
2. 2Click in the Text field to open the expression editor
3. 3Build message using {{ $json.action.data.card.name }} syntax
4. 4Add card URL and action details to the message
5. 5Preview the message format

Add Node > IF > Configure Conditions

Add conditional logic

Insert an IF node between Trello and Slack to filter which updates get posted. Configure conditions for specific list moves or comment additions. This prevents spam from minor card edits. You can filter by action type, list names, or member changes.

1. 1Add an IF node between Trello Trigger and Slack
2. 2Set condition to check action.type equals 'updateCard'
3. 3Add second condition for list changes or comments
4. 4Connect True branch to Slack node
5. 5Leave False branch empty to ignore unwanted updates

Workflow > Save > Test Workflow > Activate

Test and activate workflow

Save the workflow and test it by moving a Trello card or adding a comment. Check that the webhook fires and Slack receives the message. Review the execution log to debug any issues. Once working, activate the workflow to handle live events.

1. 1Click Save in the top right
2. 2Move a test card in your Trello board
3. 3Check the Executions tab for webhook activity
4. 4Verify message appears in your Slack channel
5. 5Toggle the workflow to Active status

This code formats different Trello actions into readable Slack messages and handles missing data gracefully. Paste it into a Function node between the IF node and Slack node.

const action = $input.all()[0].json.action;
const card = action.data.card;
const member = action.memberCreator;

const action = $input.all()[0].json.action;
const card = action.data.card;
const member = action.memberCreator;

let message = '';
let emoji = '📋';

// Handle different action types
switch(action.type) {
  case 'updateCard':
    if (action.data.listBefore && action.data.listAfter) {
      // Card moved between lists
      message = `${emoji} ${member.fullName} moved '${card.name}' from ${action.data.listBefore.name} → ${action.data.listAfter.name}`;
      emoji = action.data.listAfter.name.toLowerCase().includes('done') ? '✅' : '🔄';
    } else if (action.data.old && action.data.old.name) {
      // Card renamed
      message = `${emoji} ${member.fullName} renamed card '${action.data.old.name}' to '${card.name}'`;
    }
    break;
    
  case 'commentCard':
    const comment = action.data.text.length > 100 ? 
      action.data.text.substring(0, 100) + '...' : action.data.text;
    message = `💬 ${member.fullName} commented on '${card.name}': ${comment}`;
    break;
    
  case 'addMemberToCard':
    const addedMember = action.data.member;
    message = `👤 ${member.fullName} assigned ${addedMember.fullName} to '${card.name}'`;
    break;
    
  default:
    message = `${emoji} ${member.fullName} updated '${card.name}'`;
}

// Add card link if available
if (card.shortUrl) {
  message += ` | <${card.shortUrl}|View Card>`;
}

return {
  channel: '#product-updates',
  text: message,
  username: 'Trello Bot',
  icon_emoji: emoji
};