LiChess keeps getting better. What started out as a pretty ghetto site back in the day is now a feature-rich, highly trafficked chess site. And everything, up to this point, is free on the site, including a new shared analysis tool.
You can do shared analysis on Chess.com as well, although I believe there are some limitations to what free members can do (at least, there were limitations in the old Chess.com–I haven’t tested it yet on the new v3 server). The LiChess shared analysis tool lets you do live analysis with a friend, just like you might do postmortem in an OTB game.
I won’t do a full video on this, because Tony Rotella has done a complete walk through already. If you haven’t see it, check it out below: