Free Chess Openings Explorer
Chess opening explorers are incredibly useful, and are allowed under the rules of correspondence chess. However, many explorers, such as chess.com's own, require you to pay to register in order to go deep into the games.
Some, however, are still free. One of the best ones is www.365chess.com .
This site has a free registraion, sends no spam or any other sort of email to you, and has an easy-to-use and comprehensive database explorer that lets you see the games on the database that started with the opening you are exploring, all for free!
The database is only marginally smaller than that on chess.com. Here is a comparison of the number of games in each for different first moves:
|First Move||chess.com (paid)||365chess.com (free)|
As you can see, the difference is not huge.
Check out www.365chess.com if you are not a premium member to look through a master games database for free.