Publication : Inside Vaucanson Thomas Claveirole, Sylvain Lombardy, Louis-Noel Pouchet and Jacques Sakarovitch. http://publis.lrde.epita.fr/200506-Ciaa Tenth International Conference on Implementation and Application of Automata, 27-29 June 2005 (http://www.i3s.unice.fr/ciaa05/) This paper presents some features of the Vaucanson plateform. We describe some original algorithms on weighted automata and transducers (computation of the quotient, conversion of a regular expression into a weighted automaton, and composition). We explain how complex declarations due to the generic programming are masked from the user and finally we present a proposal for an XML format that allows implicit descriptions for simple types of automata. -- Louis-Noel Pouchet pouchet@lrde.epita.fr