# HTTP/S API Overview

Our simplest, most popular messaging API. This easy-to-use and powerful piece of code will quickly and easily integrate with your systems and applications, allowing you to send SMS messages internationally using our reliable bulk SMS messaging gateway.

## **Why use this API?**

* Extremely reliable and can be debugged easily, e.g. if you need to overcome a firewall problem.
* Can instantly send 50-100 messages in real time.
* Set up Delivery Acknowledgment, Sender ID and Message Delay.
* Supports text, Unicode, binary SMS and flash messages.
* Converts ringtones and logos into the correct format.
* Converts VCard and VCal.
* Supports extended length messages.
* Delivery acknowledgment and sender ID.
* Gateway escalation –  should your message be delayed for a predefined length of time, it can be escalated to an alternative delivery gateway; queuing lets you specify up to three prioritized queues on which your messages can be sent.
* Specify a delay of up to seven days when sending messages.
* Batch sending and two-way messaging.
* BONUS FEATURE: Conveniently check your message credits balance, query message delivery status, or redeem message credit vouchers through an API call.

## **When to use this API**

The HTTP/S API is ideal for keeping customers up-to-date about the latest changes in your business, whether it is a fantastic special offer or longer opening hours.


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# Agent Instructions: Querying This Documentation

If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://help.clickatell.com/developers-api-reference/developers-archive/sms-http-s-api/http-s-api-overview.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.
