Knowledge Center

Collection of API reference documentation for Retarus APIs. Guides and quickstarts for integrating Retarus products and services into your business. SDKs for popular web languages. Code snippets, tutorials, and sample apps for common use cases and communications solutions.

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How to send a Fax?

Retarus Fax for Applications enables developers to easily send Faxes from any application.

How to send Emails?

Sending millions of emails per hours has never been easier. Checkout the Retarus Transactional Email API.

How to send SMS?

The Retarus Enterprise SMS Service allows to send SMS via our well-defined APIs.