Trello and Twilio connect through the Trello REST API and its webhook subscription system to send SMS notifications when cards move between lists, approach due dates, or are created on boards that serve as intake or ticketing queues. This integration is used by small teams and customer-facing operations that manage workflows in Trello boards and need phone alerts for high-priority card movements without checking the board manually. The architecture requires a Trello API key and token, a middleware endpoint to receive board action events, and the Twilio Messages API to dispatch the SMS to the appropriate recipient.
What You Need Before You Start
Obtain your Trello API key by visiting https://trello.com/power-ups/admin and creating a new Power-Up, then clicking Generate a new API key on the API key page, which also shows the secret you should store alongside it. Generate a Trello user token by directing yourself to the OAuth authorization URL with your API key and the scopes read and write, and note the token value it returns after authorization. From Twilio, collect your Account SID, Auth Token, and an SMS-capable phone number, and prepare a mapping between Trello member IDs and their mobile phone numbers since Trello does not expose phone numbers on member objects. Find the board ID for the board you want to monitor by calling GET https://api.trello.com/1/members/me/boards?key={apiKey}&token={token} and noting the id field of the target board in the response array.
Step-by-Step Integration Guide
Register a Trello webhook by calling POST https://api.trello.com/1/tokens/{token}/webhooks?key={apiKey} with a JSON body containing description set to a label like SMS Notifier, callbackURL set to your middleware endpoint such as https://yourapp.com/trello/webhook, and idModel set to the board ID you want to monitor. Trello immediately sends a HEAD request to your callbackURL to verify it is reachable and returns HTTP 200, and if your endpoint does not respond to HEAD requests, registration fails with a 500 error. Ensure your middleware handles both HEAD and POST methods on the webhook path, returning HTTP 200 with no body for HEAD and processing the payload for POST. When a card moves between lists, Trello sends a POST payload with action.type equal to updateCard and action.data.listAfter and action.data.listBefore fields containing the destination and source list names and IDs. Extract action.data.card.idMembers from the payload or fetch card members separately with GET https://api.trello.com/1/cards/{cardId}/members?key={apiKey}&token={token} to get the assigned member IDs, look up each member's phone from your directory, and send the SMS via POST https://api.twilio.com/2010-04-01/Accounts/{AccountSid}/Messages.json with a body describing the card name and the list it moved to.
Common Issues and How to Fix Them
Trello webhooks expire when the associated token is revoked or expires, which can happen if the token was generated with a short expiry or if the Power-Up is removed from the workspace, causing your integration to stop receiving events silently. Implement a monitoring job that calls GET https://api.trello.com/1/tokens/{token}/webhooks?key={apiKey} to list active webhooks and verify your webhook ID still appears in the response, and re-register the webhook and alert your team if it is missing. Trello sends a webhook event for every action on the board including comment additions, label changes, attachment uploads, and member changes, generating a high volume of irrelevant events. Filter events in your middleware by checking action.type against an allow-list of relevant types such as updateCard, createCard, and addMemberToCard before doing any processing or Twilio API calls. The Trello API enforces rate limits of 100 requests per 10 seconds and 100 requests per 10 seconds per token, and a high-activity board can push your webhook handler to exceed this if it makes multiple card-read calls per event. Cache recently fetched card and member objects for 30 seconds in your middleware to avoid redundant Trello API calls when multiple events arrive for the same card in quick succession.
How to Get More from This Integration
Build a due date reminder by running a daily scheduled job that calls GET https://api.trello.com/1/boards/{boardId}/cards?key={apiKey}&token={token}&fields=name,due,idMembers and filters the result for cards where the due date is within the next 24 hours and due_complete is false, then sends each assigned member an SMS listing the card name and due time. Create a new card intake alert by filtering for action.type equal to createCard in your webhook handler, checking that action.data.list.name equals your intake list name such as New Requests, and sending an SMS to a fixed team phone number announcing a new card so someone picks it up immediately. Add a Trello card command-and-control loop by routing inbound Twilio SMS from team members to your middleware, parsing commands like MOVE {cardId} DONE and calling PUT https://api.trello.com/1/cards/{cardId}?key={apiKey}&token={token}&idList={doneListId} to move the card to your Done list by SMS without opening Trello. Use Trello custom fields on cards to store an escalation phone number per card, readable via GET https://api.trello.com/1/cards/{cardId}/customFieldItems?key={apiKey}&token={token} and mapping the custom field ID to the phone value, so cards representing external clients can route SMS alerts to the client's own phone rather than an internal team member.
Conclusion
Trello and Twilio together turn your Kanban board into a live notification system that sends SMS alerts directly to the right person when a card demands attention. Contact Telphi Consulting to build this integration for your Trello boards and team workflows.
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