Chess Opening Explorer

Openings are a tree, so walk it

Almost every opening name you have heard is a position, not a plan. The Italian Game is the position after 1.e4 e5 2.Nf3 Nc6 3.Bc4 - nothing more mysterious than that. Learning openings from a list of names is hard for the same reason learning a city from a list of street names is hard: the names are real, but the thing that makes them make sense is how they connect.

So this page is the connections. Start from the initial position, play a move, and watch what it rules out. Play 1.e4 and the five replies to it appear while every queen's pawn opening quietly disappears. Play 1...c5 and you are in the Sicilian, one move in, with eighteen openings gone. Nothing is memorised; the shape does the work.

Every position that has a name says so the moment you reach it, with a link to the page that teaches it properly. And every position that has no name says that too - which is most of chess, and worth seeing.

What the explorer actually shows

• The openings still reachable from the position on the board, grouped the way the openings hub groups them, and narrowing with every move you play.
• The moves the catalog knows from here, each labelled with how many openings lie down it - so a move played by ten openings looks different from one played by one.
• The name of the position, the moment it has one, with its ECO code and a link to the full page.
• The line you have walked, in ordinary numbered notation, with every move clickable so you can step back to any point without starting over.
• Whether you have left the book - because playing a legal move nobody in this catalog plays is a normal thing to do, not an error.

How to use it

1. 1

   Play a move

   Click a piece and then the square it goes to, or pick one of the moves listed beside the board. The listed moves are the ones this catalog knows; the board accepts any legal move at all.

2. 2

   Watch the list narrow

   The openings panel shows what is still reachable. It only ever shrinks, because a move can rule an opening out but can never bring one back.

3. 3

   Stop when something is named

   When the position carries a name, a card says so - the opening, its ECO code, and a link to the page that teaches it. That is the moment to go and read.

4. 4

   Step back and take the other branch

   Every move in the line is a button. Click any earlier move to return to it, then play something else. Comparing two branches from one position is the fastest way to understand what a choice actually costs.

Three walks worth taking

Common mistakes with openings

• Memorising move lists without the reason. A line you cannot explain collapses the moment your opponent plays the fifth move differently - and below master level, they almost always do.
• Learning an opening for both colours at once. Pick one thing to play as White and one answer to 1.e4, get comfortable, and add the rest later.
• Judging an opening by how exciting it sounds. The King's Gambit is thrilling and hard to play well; the London System is dull and wins games. Reputation and results are different measurements.
• Assuming a name means a plan. The Sicilian is a family with wildly different characters inside it - the Najdorf and the Dragon share a first move and very little else.
• Treating a transposition as a trick. Different move orders reaching the same position is ordinary, and it is why the explorer keys everything on the position rather than the route to it.
• Blaming the opening for a bad game. Most games below 1800 are decided by a hanging piece long after the opening ended - the opening only has to leave you a playable position.

Chess opening explorer FAQ