Nimzo-Indian Defense

The Nimzo-Indian Defense (ECO code E20) is a chess opening that begins with 1. d4 Nf6 2. c4 e6 3. Nc3 Bb4. Black pins the knight with ...Bb4, controlling e4 without committing pawns. Named after Aron Nimzowitsch. One of Black's most respected defenses — Kasparov, Kramnik, and Carlsen all played it extensively.

The main line of the Nimzo-Indian Defense is 1. d4 Nf6 2. c4 e6 3. Nc3 Bb4. It is classified under ECO code E20 and falls in the Indian Defense family of chess openings. From this starting position, both sides have well-established plans — White typically continues with natural developing moves while Black follows the response patterns described above.

The Nimzo-Indian Defense is more strategic than tactical, which can make it harder for beginners to feel like they're "doing something" — but the upside is fewer forced lines to memorize. If you understand the typical pawn structure and middlegame plans, you can play this opening from move 1 without needing 15 moves of theory. Pair it with engine review at chess.rodeo to see where your understanding breaks down.

The Nimzo-Indian Defense is classified as ECO code E20. ECO (Encyclopaedia of Chess Openings) is the standard five-letter classification system developed by Chess Informant in the 1970s — A-codes cover flank openings, B-codes 1.e4 replies that aren't 1...e5, C-codes 1.e4 e5 openings, D-codes 1.d4 d5 systems, and E-codes Indian Defenses. You can browse all openings by ECO code in our free opening database.

Use chess.rodeo for full Stockfish analysis of your Nimzo-Indian Defense games — no account required, no daily cap, no paywall. Paste your PGN and get instant engine evaluation on every move, including the opening phase. For move-by-move replay without engine output, use our free PGN viewer. Both are completely free with no signup.