Logisim

Logisim is an educational program written by Carl Burch that allows for creation and testing of logic circuits. Its project format is an XML-based format with the extension ".circ". Some project files may have references to others; if the reference cannot be resolved automatically, Logisim prompts the user to select the file referred to.

Development was stopped on the original version of Logisim in 2014. Following this, a group of Swiss schools has continued to add features to a fork called "Logisim-Evolution", which shares most of its format with the original Logisim, although apparently due to the addition of "a parser that alters the name of the components to satisfy VHDL requirements for variable names", there are some problems with backwards compatibility.

Identification
The root element has the tag name "project". The next line after that will be the text "This file is intended to be loaded by Logisim (http://www.cburch.com/logisim/).", or "This file is intended to be loaded by Logisim-evolution (https://github.com/reds-heig/logisim-evolution).", in the case of Logisim-Evolution.

Software

 * Sourceforge page of original
 * Sourceforge page of Logisim-Evolution (Not in use since 2015)
 * Github page of Logisim-Evolution

Links

 * Website of original
 * Circuitverse: Essentially a reimplementation in Javascript, not compatible format-wise
 * Logisim