Title: Computer assisted proofs for non-symmetric planar choreographies and for stability of the Eight Authors: T. Kapela (1) and C. Sim\'o (2) (1) Jagiellonian University, Institute of Computer Science, Nawojki, 11, 30-072 Krak\'ow, Poland. (2) Dept. de Matem\`{a}tica Aplicada i An\`{a}lisi, Univ. de Barcelona, Gran Via 585, 08007 Barcelona, Spain. E-mail: kapela@ii.uj.edu.pl, carles@maia.ub.es Abstract We present a general method to produce computer assisted proofs of the existence of choreographies in the N-body problem. This method allows to verify rigorously numerical data from computer simulations. As an example we use it to prove the existence of non-symmetric choreographies with 6 and 7 bodies. The method provides estimates for the initial conditions and for the monodromy matrix of the choreography. These data are used to show linear stability of the Eight solution restricted to the plane.