diff --git a/Developer-documentation.md b/Developer-documentation.md
index 5f9813e..ca5ca68 100644
--- a/Developer-documentation.md
+++ b/Developer-documentation.md
@@ -45,6 +45,55 @@ There are two different kinds of functions that perform data validation:
 
 It is not unusual for a parser function to call a validator function to validate its whole input before extracting the fields.
 
+## Functions
+
+This section gives an overview of the important source files and functions.
+
+### caff_tools.c
+
+This file contains functions that are used to validate and parse CAFF files.
+
+`parse_caff_header` is used to parse the header of a CAFF file.
+
+`validate_caff_credits` is used to validate the credits section of a CAFF file.
+
+`validate_caff_animation` is used to validate a single CAFF animation section.
+
+`validate_caff_file` is used to validate the whole CAFF file.
+
+`parse_caff_get_first_ciff` is used to parse a CAFF file and extract the first CIFF image from it.
+
+### ciff_tools.c
+
+This file contains functions that are used to validate and parse CIFF images.
+
+`validate_ciff` is used to validate a CIFF image.
+
+`parse_ciff_get_pixel_data` is used to parse a CIFF image and to find the location of pixel data.
+
+### magic_memory.c
+
+This file contains our own MagicMemory library that provides memory allocation functions.
+
+`magic_memory_begin` is used to create a MagicMemory context that can be used with other MagicMemory functions later.
+
+`magic_malloc` is the same as the standard `malloc`, but the pointer is also added to a context. Contexts are used to keep track of pointers so that they won't be lost. A context is basically a linked list of pointers.
+
+### main.c
+
+`main` is the entrypoint of the previewer module.
+
+`perform_extraction` takes care of the preview extraction process: it calls parser and validator functions and other helper functions.
+
+### utils.c
+
+`read_file_to_mem` is used to read CAFF files into memory.
+
+
+### libtarga.c
+
+This files contains the [LibTarga](https://research.cs.wisc.edu/graphics/Gallery/LibTarga/) library by Alex Mohr.
+
 # CAFF previewer wrapper
 This module makes communication between the previewer and the web client possible.