Dr. Geo was initially developed in C++ with Scheme scripting,[2][3] then in various versions of Smalltalk with Squeak, Etoys_(programming_language)[4] for One Laptop per Child[5] Pharo then Cuis-Smalltalk.

Dr. Geo manipulates different kinds of objects such as points, lines, circles, vector, values, geometric transformations, scripts.

Dr. Geo is equipped with the classic line, ray, segment and vector.

[7] It allows to add new objects to Dr. Geo: new transformations like circle inversion, tedious constructions involving a lot of intermediate objects or constructions involving script (also named macro-script).

It is also the language used for user programming: to extend Dr. Geo with arbitrary computing operations (Smalltalk script) and to define a geometric sketch entirely with programming instructions (Smalltalk sketch).

[10] Smalltalk itself is a high level language, carefully crafted iteratively for about 10 years at Palo Alto Research Center.

A Fibonacci spiral programmed[11] with geometric transformations (rotation, translation and homothety).

Smalltalk sktech can be used to design interactive sketch illustrating a numerical analysis method.

Smalltalk sketch can be coded in native languages, currently in French and Spanish.