full-stack-tech/emdash-plugin-twilio-sms

This project is a Twilio SMS plugin for EmDash CMS, a content management system. It lets a site running EmDash send text messages to lists of subscribers, such as parents on a school mailing list, and manage the whole lifecycle of those messages properly. The plugin handles SMS broadcasts to tagged groups of subscribers, so an admin could send a single message to everyone tagged as a parent, for example. It also takes care of opt-out compliance: if someone replies STOP, they are automatically unsubscribed and will never receive another broadcast or one-off message, while START re-subscribes them and HELP gets a canned reply. These inbound replies are verified using Twilio's signature check before anything is changed, so the system can trust that the message really came from Twilio and not a spoofed request. Beyond broadcasts, it logs delivery status through Twilio's callback system, so you can see whether a text actually reached someone. It also estimates how many SMS segments a message will take up, since long messages get split and billed differently depending on whether they use standard characters or characters outside the basic GSM alphabet. There is also a bridge to a forms plugin, so when someone submits or has a form approved, they can automatically receive a text with a template message. While it is built specifically for EmDash, the author also exposed a framework agnostic core: phone number formatting, SMS segment counting, sending through Twilio's API, and webhook signature verification, which only depend on standard web APIs. That means these pieces can be reused directly in any Worker or Node project, without needing EmDash at all. The project was pulled out of a real production site for a school parent-teacher association, so the compliance and delivery-tracking logic reflects what that site actually needed. It is licensed under MIT.