The Adobe® FrameMaker® Developer Kit (FDK) is a set of C libraries and header files that allow you to write Application Programmer Interface (API) clients or plug-ins using the C or C++ programming language. Using the FDK, an API client can perform interactive user tasks and more. It gives programmers direct access to all the objects in a FrameMaker session or document. This includes graphics, text, markers, paragraphs, formats, and more.

FrameMaker ExtendScript

ExtendScript is an extended implementation of JavaScript that provides a scripting interface for FrameMaker and many other Adobe applications. For more information on ExtendScript, see JavaScript Tools Guide.
ExtendScript is easy to learn, especially if you are familiar with FDK API and a scripting language like JavaScript.
Refer to the additional resources section below for more information and samples on ExtendScript.

Structure Application Development

Developing a FrameMaker structure application can appear complex at first. True, there is ultimately a lot to learn, but the overall process is easily broken down into manageable topics. Read further to develop your own structured FrameMaker templates and XML or SGML applications.

Customizing DITA

DITA Specialization is the process of creating new designs based on existing designs. A specialization can reuse elements from higher-level designs. You can specialize DITA to create customized informa­tion models that meet your business requirements while retaining the benefits of the existing DITA architecture.
DITA customization allows you to easily customize the document shells. You can also remove domains or individual elements.
DITA customization using the Plugin is an easy UI-driven way of customizing DITA.  

MIF (Maker Interchange Format)

MIF (Maker Interchange Format) is a FrameMaker file format that allows you to easily write external programs that convert FrameMaker document files into foreign files (files in another word processing or desktop publishing format), and foreign files into FrameMaker document files. You can use MIF files with database publishing applications, which allow you to capture changing data from databases and format the data into high-quality documents containing both text and graphics information. You use the database to enter, manipulate, sort, and select data. You use FrameMaker to format the resulting data. You use MIF files as the data interchange format between the database and FrameMaker.

INI Reference

Open and edit the FrameMaker INI files in any text editor (such as Notepad), to easily apply available configuration settings which FrameMaker checks at launch.

Additional Resources

CMS Connector

FrameMaker can be integrated with a variety of Content Management System (CMS). You can create your own CMS connector using FDK. Below you will find information and source code for one production ready and two sample connectors written between Adobe CQ  and FrameMaker v10 and v11. The FrameMaker 11 production ready and sample connectors have been improved to leverage the new “CMS connector framework” that we are providing as part of FrameMaker 11. Using this framework, developers will be able to build a more seamless connector to FrameMaker 11 and with less effort! Read on further to know more about these connectors and how to create your own CMS connector either from scratch or using one of the connectors provided as a starting point.
Production ready connector between FrameMaker 11 and Adobe CQ5.5  (CRX 2.3)
Source Code of Connector
For more details Read the blog.
Sample connector between FrameMaker 11 and Adobe CQ  (CRX 2.1 to CRX 2.3)
For more details Read the blog.
Sample connector between FrameMaker 10 and Adobe CQ  (CRX 2.1 to CRX 2.2)
Download the code of the sample connector (which can be enhanced and also used to build connectors to other CMS)