Is there a free online chess repertoire tool? Is there a free online chess repertoire tool? It can be some place where you register, save variations and comments, and navigate with a board what you do. I was used to chessply, but apparently it disappeared.
In addition to the other answers, there are a few sites to consider. These include annotation and comment features as mentioned by the OP.
Listudy.org
Upload a PGN and then you play the computer interactively. You play moves from your repertoire and the computer plays the opponent moves. This is also open source.
ChessTempo.com
Similar functionality in the &quot;Opening Trainer.&quot; The interface is a bit different but it tracks what lines you have learned a bit differently which is nice.
lichess.org
As B.Swan has pointed out in a comment.

There are also other related sites worth exploring to understand their capabilities and how they may supplement the resources above.
ChessTree.com
Import/export PGNs. Search databases, get statistics. See opening relationships in a graphical tree.
OpeningTree.com
Import/export PGNs.  Import and analyze a user's openings from a database, PGN, etc, including popular online chess sites.