> For the complete documentation index, see [llms.txt](https://fundamental-interactions-inc.gitbook.io/finteractions.com-restapi/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://fundamental-interactions-inc.gitbook.io/finteractions.com-restapi/overview.md).

# OVERVIEW

INTRODUCTION

Fundamental Interactions market center technology API has been deployed for subscribers to gain fast and easy integration. Subscribers can utilize the API for user creation, order and market data access for integration over the web. Subscribers' applications, which can be desktop, web portal, or black box based, will communicate with the market center servers using different types of messages. These messages are made available through the REST API layer.

The API messages are backward and forward compatible. New messages and new fields can be added to the API, but existing messages and fields will never change, so users of previous API versions will not be affected when new versions are released. If a subscriber wants access to new messages or fields, they can simply add them to their message structure. Most of the messages and related fields are self-explanatory.

Any questions about the REST API can be directed to Fundamental Interactions support email: <support@fundamentalinteractions.com>


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