# Communications

> An index and topic collection covering Communications Platform as a Service (CPaaS) and messaging-and-voice infrastructure APIs. This network gathers providers offering programmable SMS, MMS, voice, video, transactional and marketing email, chat, push notifications, in-app messaging, and delivera...

This is the **Communications** topic area of [API Evangelist](https://apievangelist.com) — a network of focused knowledge bases drawn from 16 years of independent API research by Kin Lane. Browse all areas at https://apievangelist.com/areas/.

## Services & Tools
- [Ably](https://providers.apis.io/providers/ably/) (repo: https://github.com/api-evangelist/ably)
- [Aircall](https://providers.apis.io/providers/aircall/) (repo: https://github.com/api-evangelist/aircall)
- [Airship](https://providers.apis.io/providers/airship/) (repo: https://github.com/api-evangelist/airship)
- [Amazon Pinpoint](https://providers.apis.io/providers/amazon-pinpoint/) (repo: https://github.com/api-evangelist/amazon-pinpoint)
- [Amazon SES](https://providers.apis.io/providers/amazon-ses/) (repo: https://github.com/api-evangelist/amazon-ses)
- [Amazon SNS](https://providers.apis.io/providers/amazon-sns/) (repo: https://github.com/api-evangelist/amazon-sns)
- [api.video](https://providers.apis.io/providers/api-video/) (repo: https://github.com/api-evangelist/api-video)
- [Bandwidth](https://providers.apis.io/providers/bandwidth/) (repo: https://github.com/api-evangelist/bandwidth)
- [Braze](https://providers.apis.io/providers/braze/) (repo: https://github.com/api-evangelist/braze)
- [CallRail](https://providers.apis.io/providers/callrail/) (repo: https://github.com/api-evangelist/callrail)
- [CleverTap](https://providers.apis.io/providers/clevertap/) (repo: https://github.com/api-evangelist/clevertap)
- [ClickSend SMS](https://providers.apis.io/providers/clicksend-sms/) (repo: https://github.com/api-evangelist/clicksend-sms)
- [Courier](https://providers.apis.io/providers/courier/) (repo: https://github.com/api-evangelist/courier)
- [Crisp](https://providers.apis.io/providers/crisp/) (repo: https://github.com/api-evangelist/crisp)
- [Customer.io](https://providers.apis.io/providers/customer-io/) (repo: https://github.com/api-evangelist/customer-io)
- [Daily.co](https://providers.apis.io/providers/daily-co/) (repo: https://github.com/api-evangelist/daily-co)
- [Dialpad](https://providers.apis.io/providers/dialpad/) (repo: https://github.com/api-evangelist/dialpad)
- [Dolby](https://providers.apis.io/providers/dolby/) (repo: https://github.com/api-evangelist/dolby)
- [Iterable](https://providers.apis.io/providers/iterable/) (repo: https://github.com/api-evangelist/iterable)
- [JustCall](https://providers.apis.io/providers/justcall/) (repo: https://github.com/api-evangelist/justcall)
- [Klaviyo](https://providers.apis.io/providers/klaviyo/) (repo: https://github.com/api-evangelist/klaviyo)
- [Knock](https://providers.apis.io/providers/knock/) (repo: https://github.com/api-evangelist/knock)
- [LiveKit](https://providers.apis.io/providers/livekit/) (repo: https://github.com/api-evangelist/livekit)
- [Loops](https://providers.apis.io/providers/loops/) (repo: https://github.com/api-evangelist/loops)
- [Mailchimp](https://providers.apis.io/providers/mailchimp/) (repo: https://github.com/api-evangelist/mailchimp)
- [MailerLite](https://providers.apis.io/providers/mailerlite/) (repo: https://github.com/api-evangelist/mailerlite)
- [MailerSend](https://providers.apis.io/providers/mailersend/) (repo: https://github.com/api-evangelist/mailersend)
- [Mailgun](https://providers.apis.io/providers/mailgun/) (repo: https://github.com/api-evangelist/mailgun)
- [Mailjet](https://providers.apis.io/providers/mailjet/) (repo: https://github.com/api-evangelist/mailjet)
- [Mailtrap](https://providers.apis.io/providers/mailtrap/) (repo: https://github.com/api-evangelist/mailtrap)
- [MessageBird](https://providers.apis.io/providers/messagebird/) (repo: https://github.com/api-evangelist/messagebird)
- [Mux](https://providers.apis.io/providers/mux/) (repo: https://github.com/api-evangelist/mux)
- [OneSignal](https://providers.apis.io/providers/onesignal/) (repo: https://github.com/api-evangelist/onesignal)
- [Plivo](https://providers.apis.io/providers/plivo/) (repo: https://github.com/api-evangelist/plivo)
- [Postmark](https://providers.apis.io/providers/postmark/) (repo: https://github.com/api-evangelist/postmark)
- [PubNub](https://providers.apis.io/providers/pubnub/) (repo: https://github.com/api-evangelist/pubnub)
- [Pusher](https://providers.apis.io/providers/pusher/) (repo: https://github.com/api-evangelist/pusher)
- [Resend](https://providers.apis.io/providers/resend/) (repo: https://github.com/api-evangelist/resend)
- [RingCentral](https://providers.apis.io/providers/ringcentral/) (repo: https://github.com/api-evangelist/ringcentral)
- [Sendbird](https://providers.apis.io/providers/sendbird/) (repo: https://github.com/api-evangelist/sendbird)
- [SendGrid](https://providers.apis.io/providers/sendgrid/) (repo: https://github.com/api-evangelist/sendgrid)
- [Sinch](https://providers.apis.io/providers/sinch/) (repo: https://github.com/api-evangelist/sinch)
- [Stream](https://providers.apis.io/providers/stream-io/) (repo: https://github.com/api-evangelist/stream-io)
- [Telesign](https://providers.apis.io/providers/telesign/) (repo: https://github.com/api-evangelist/telesign)
- [Telnyx](https://providers.apis.io/providers/telnyx/) (repo: https://github.com/api-evangelist/telnyx)
- [Twilio](https://providers.apis.io/providers/twilio/) (repo: https://github.com/api-evangelist/twilio)
- [Vonage](https://providers.apis.io/providers/vonage/) (repo: https://github.com/api-evangelist/vonage)
- [Zoom](https://providers.apis.io/providers/zoom/) (repo: https://github.com/api-evangelist/zoom)

## Common Features
- **Programmable SMS, MMS, and Voice**: CPaaS providers expose programmable APIs for sending and receiving SMS and MMS messages, placing and routing voice calls, and managing phone number inventory across the global PSTN.
- **Transactional and Marketing Email**: Email APIs handle high-volume transactional sends, marketing campaigns, template rendering, list management, and deliverability monitoring through ESP infrastructure.
- **Real-Time Video and Audio**: Video and real-time platforms expose APIs and SDKs for embedding live video calls, broadcasts, conferences, and low-latency audio rooms into applications.
- **Push Notifications and In-App Messaging**: Push providers deliver native iOS and Android push notifications, web push, and in-app messages at scale across FCM, APNs, and proprietary delivery infrastructure.
- **Realtime Chat and Pub/Sub**: Realtime APIs provide WebSocket-based pub/sub channels, chat rooms, presence, and message history for collaborative and social applications.
- **Notification Orchestration and Multi-Channel Delivery**: Orchestration platforms unify SMS, email, push, chat, and in-app channels behind a single API with templating, preference management, and routing logic.
- **Deliverability and Reputation Management**: Deliverability tooling covers IP warmup, SPF/DKIM/DMARC, bounce and spam handling, suppression lists, and engagement-based sender reputation analytics.
- **Number Provisioning and Verification**: Communications APIs manage phone number purchase, porting, regulatory compliance, and verification flows like one-time passwords and silent network auth.

## Use Cases
- **Two-Factor Authentication and OTP Delivery**: Applications use SMS, voice, and email APIs to deliver one-time passcodes and verification messages for login, signup, and high-risk action confirmation.
- **Transactional Notifications**: Platforms send order confirmations, shipping updates, password resets, and account alerts through email, SMS, and push APIs as part of core product workflows.
- **Customer Engagement Campaigns**: Marketing teams orchestrate multi-channel email, SMS, and push campaigns using providers like Braze, Iterable, Customer.io, and Klaviyo to drive retention and lifecycle messaging.
- **Live Video and Audio Embeds**: Telehealth, education, and collaboration apps embed branded live video and audio experiences using Daily.co, Agora, LiveKit, Zoom SDKs, and Dolby.
- **Contact Center and Programmable Voice**: Support and sales teams build programmable IVRs, click-to-call, call tracking, and conversational voice flows on Twilio, Vonage, Dialpad, and RingCentral.
- **Realtime Chat and Social Features**: Apps add direct messaging, group chat, presence, and live commenting using Sendbird, Stream, PubNub, Ably, and Pusher.
- **Operational and Incident Alerting**: Engineering and SRE teams page on-call staff and broadcast incident status via SMS, voice, push, and email through Knock, Courier, and CPaaS providers.

## Related Areas
- [Bots](https://bots.apievangelist.com): An index and topic collection covering chatbots, conversational agents, and bot frameworks across messaging, voice, a...
- [Support](https://support.apievangelist.com): An index and topic collection covering customer support, help desk, ticketing, knowledge base, and live chat APIs. Cu...

## More
- [Latest Communications stories](/stories/)
- [All API Evangelist topic areas](https://apievangelist.com/areas/)
- [API Evangelist network index (llms.txt)](https://apievangelist.com/llms.txt)