# Clickatell API Docs

## Channels

* [**WhatsApp & SMS (One API)**](https://help.clickatell.com/developer/channels/whatsapp-and-sms-one-api)**:** Communicate with customers via multiple messaging channels (WhatsApp and SMS) using a single integration.
* [**SMS only**](https://help.clickatell.com/developer/channels/sms-only)**:** Enable one- and two-way SMS communication with your customers.

## Applications

* [**Chat 2 Pay API**](https://help.clickatell.com/developer/applications/chat-2-pay-api)**:** Send payment requests to customers and facilitate payments via chat for secure, contactless payment experiences.
* [**Chat Flow External Link Handler API**](https://help.clickatell.com/developer/applications/chat-flow-external-link-handler-api)**:** Direct customers to an external web page from within a Chat Flow conversation and return with additional data. 

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