Slap V2 client prototype has been implemented in CASSIS
You can select the SLAP service in the Cassis database settings menu and display the lines over spectra and click on it to have the informations about the lines. The SLAP database path is http://sesam.obspm.fr/19.04/vamdc/slap/ For more information, see talk about CASSIS at IVOA Groningen 2019-Netherlands