The labsar algorithm aims to coregistrate SAR images without using a DEM. Designed by Jean-Marie Nicolas, this algorithm is easy to use and gives good results for both interferometry and mouvement estimation. For this article, I tested the interferometric performances of Labsar while Laurane Charrier and Cyril Thomas verifies the mouvement estimation. We worked on the very beautiful PAZ images over the Chamonix area and the Bosson glacier. Help by Jean-Marie, we tried to explain the methodology as clearly as possible. I was very happy to write this article with this nice team, and especially with Laurane.