The API Viewer allows browsing declarations, constants, and types from an API text file or Jet database. Items can be copied to the clipboard and pasted into Visual Basic code. It includes the WIN32API text file and lets users convert text files to databases for faster loading. Users can load an API file, view items by type, add items to a selected list, copy the list to the clipboard, and remove items. The File menu offers options to load text/database files, convert text to database, and exit.