Twilio

Twilio API provides comprehensive cloud communications platform with HTTP Basic authentication using API keys. Supports 200 endpoints covering voice calls, SMS, MMS, WhatsApp, email (SendGrid), video, and verification services with global reach in 180+ countries.

Messaging API enables sending and receiving messages across multiple channels with real-time route optimization, deliverability scoring, and fraud detection. Voice API supports outbound and inbound calls with TwiML markup for call control, IVR systems, call recording, conferencing, and SIP trunking. Programmable Video for embedded video calling. Verify API for multi-channel user authentication.

Webhooks provide real-time notifications for call progress events, message status updates, and recordings. Twilio Functions serverless environment for building communication apps without infrastructure. Studio drag-and-drop workflow builder. Phone number management including toll-free, 10DLC, short codes, and alphanumeric sender IDs.

Official SDKs for JavaScript, Python, Java, PHP, C#, and Ruby. Comprehensive API documentation with code samples and tutorials. Free trial available with pay-as-you-go pricing. Production environment. Rate limits vary by endpoint. Ideal for customer notifications, two-factor authentication, appointment reminders, marketing campaigns, contact centers, and communication workflow automation.