Graph is a generalised data grapher. The "engine room" is the program EDAListplot which was written in the Mathematica programming language in 1995 by David M. Harrison and is part of the Experimental Data Analyst package which is marketted by Wolfram Research Inc., the inventors of Mathematica.
The interface to the program uses the J/Link toolkit, which allows a Java program to communicate with Mathematica via MathLink protocols. The same set of Java programs communicates with the user's browser with straight HTML and JavaScript. J/Link was written by Todd Gayley, Director of Java Technology, Wolfram Research Inc.
The interface to the program was written by and is Copyright © 1999, 2000 Solomon R.C. Douglas and David M. Harrison.