Glade (Gds, Lef And Def Editor), is a IC layout and schematic editor capable of reading and writing common EDA formats. With built in DRC, extraction and LVS you can generate and verify schematics and layout in a single customisable tool. Glade can load and display large design databases with its fast, lightweight object-oriented database. Released nearly 20 years ago now, Glade was the first free layout editor available for Windows. Glade uses the Qt cross-platform GUI toolkit for a modern GUI running on Windows, Mac and Linux, with OpenGL for hardware accelerated graphics when available to give superior display speeds, but also supports software rendering for older hardware. Glade is extendable using Python scripting, allowing access to the database and gui via SWIG wrapping of C++ functions.

Some excellent Youtube videos by Brad Minch of the University of Olin: