ExpressionEngine® User Guide

Add-On Development

Guidelines, reference material, and tutorials for developing add-ons for ExpressionEngine.

Legacy Documentation

Many of the libraries and helpers available in ExpressionEngine 2 continue to function as expected. They are earmarked for replacement in the future, but are not yet deprecated. Use these freely until replacement libraries or services are created.

For legacy documentation of libraries that were inherited from CodeIgniter, please refer to the CodeIgniter documentation.