About SMS SDK

SMS SDK is an open-source TypeScript library from OpenCore that sends and receives SMS through Twilio, Telnyx, Plivo, Vonage, Bandwidth, and Sinch with one API.

SMS SDK (@opencoredev/sms-sdk on npm) is an open-source TypeScript library for sending and receiving transactional SMS. One send() call works with Twilio, Telnyx, Plivo, Vonage, Bandwidth, and Sinch, and parseSmsWebhook() turns each provider’s delivery and inbound webhooks into one verified event shape. It runs on Node.js 20 or later and Bun 1.1 or later, and it has no runtime dependencies.

Why it exists

Every SMS provider has its own client library, its own error codes, and its own webhook format. Switching providers, or adding a second one as a fallback, usually means rewriting the code that sends messages and the code that receives status updates. SMS SDK puts one typed API in front of all six, so the provider becomes a configuration choice.

It is also strict about the one mistake that costs real money and annoys real people: sending the same text twice. send() resolves only when a provider accepted the message. When the outcome is unknown, it throws HandoffUnknownError and never retries or falls back on its own. How sending works explains each outcome.

How provider behavior is documented

Each adapter relies on provider facts: endpoints, error codes, signature schemes, and which errors mean a message was definitely refused. PROVIDERS.md lists every one of those facts with a link to its source, and says what could not be confirmed. A provider is marked partial when part of its behavior is undocumented.

Who builds it

SMS SDK is built by OpenCore and maintained by Leo. The code is MIT licensed and lives at github.com/opencoredev/sms-sdk. There is no paid tier and no hosted service: the library talks directly to the providers you configure, with your own accounts.

SMS SDK is not affiliated with or endorsed by Twilio, Telnyx, Plivo, Vonage, Bandwidth, or Sinch. Their names identify the services the adapters connect to.

Get in touch

See Contact for questions, bug reports, and security issues, and Privacy for what this site and the library collect.