Files with the AEPX extension are used by a tool for creating special effects and compositions (combining image layers into one whole in the post-production phase) called Adobe After Effects. AEPX files are used to store projects created in the program. It is a text file containing code in the XML markup language. It contains data on project settings and the location of video materials used in the project.

After Effects is a film post-production tool developed by Company of Science and Art and now supported by Adobe Systems.