Chess Openings

3810 ECO lines with main-line moves, diagrams and variations trees. Search by moves or name, walk any move order in the opening explorer, or browse the full encyclopedia by ECO volume — every family with its code range and defining move order.

Flagship openings

Sicilian DefenseB202 plies

French DefenseC002 plies

English OpeningA101 plies

Caro-Kann DefenseB102 plies

Queen's Pawn GameA401 plies

Queen's Pawn GameA412 plies

Queen's Pawn GameD002 plies

Dutch DefenseA802 plies

Alekhine DefenseB022 plies

Indian DefenseA452 plies

Zukertort OpeningA041 plies

Zukertort OpeningA052 plies

Zukertort OpeningA062 plies

Scandinavian DefenseB012 plies

Réti OpeningA093 plies

Nimzowitsch DefenseB002 plies

Modern DefenseB062 plies

King's Pawn GameB001 plies

King's Pawn GameC202 plies

Van Geet OpeningA001 plies

Bird OpeningA021 plies

Pirc DefenseB002 plies

Polish OpeningA001 plies

King's Indian AttackA073 plies

The encyclopedia by ECO volume

Grouped after the ECO volume scheme: click a family for its head position, the variations tree and every catalogued line. The board thumbnail shows the family after its defining first moves.

A — Flank openings B — Semi-open games C — Open games & French D — Closed & semi-closed E — Indian defenses

A — Flank openings 817 lines

ECO	Family	Defining moves	Lines
A00	Amar Opening	1. Nh3	3
A00	Amsterdam Attack	1. e3 e5 2. c4 d6 3. Nc3 Nc6 4. b3 Nf6	1
A00	Anderssen's Opening	1. a3	2
A00	Barnes Opening	1. f3	5
A00	Clemenz Opening	1. h3	2
A00	Creepy Crawly Formation	1. h3 d5 2. a3 e5	1
A00	Formation	1. a3 e5 2. b3 d5 3. c3 Nf6 4. d3 Nc6 …	2
A00	Global Opening	1. h3 e5 2. a3	1
A00	Grob Opening	1. g4	20
A00–A07	Hungarian Opening	1. g3	20
A00	Kádas Opening	1. h4	9
A00	Lasker Simul Special	1. g3 h5	1
A00	Mieses Opening	1. d3	4
A00–A05	Polish Opening	1. b4	27
A00	Saragossa Opening	1. c3	1
A00	Sodium Attack	1. Na3	4
A00	Valencia Opening	1. d3 e5 2. Nd2	1
A00	Van Geet Opening	1. Nc3	30
A00	Van't Kruijs Opening	1. e3	5
A00	Ware Opening	1. a4	7
A01–A06	Nimzo-Larsen Attack	1. b3	18
A02–A03	Bird Opening	1. f4	27
A04–A40	Colle System	1. d4 g6 2. Nf3 Bg7 3. e3 c5 4. Bd3 Qa5+	3
A04–A42	Modern Defense	1. d4 g6 2. h4 Nf6 3. h5	11
A04	Zukertort Defense	1. Nf3 Nh6 2. d4 g6	2
A04–A41	Zukertort Opening	1. Nf3	47
A05–A08	King's Indian Attack	1. Nf3 d5 2. g3	27
A09–A14	Réti Opening	1. Nf3 d5 2. c4	43
A10–A39	English Opening	1. c4	174
A15	English Orangutan	1. c4 Nf6 2. b4	2
A40	Australian Defense	1. d4 Na6	1
A40–A79	Benoni Defense	1. d4 c5	61
A40	Borg Defense	1. d4 g5	1
A40	English Defense	1. d4 b6	7
A40	Englund Gambit	1. d4 e5	9
A40	Englund Gambit Declined	1. d4 e5 2. d5	7
A40	Horwitz Defense	1. d4 e6	2
A40	Kangaroo Defense	1. d4 e6 2. c4 Bb4+	2
A40	Mikenas Defense	1. d4 Nc6	4
A40	Montevideo Defense	1. d4 Nc6 2. d5 Nb8	1
A40	Polish Defense	1. d4 b5	2
A40–A42	Pterodactyl Defense	1. d4 g6 2. c4 Bg7 3. Nc3 c5 4. e3	8
A40–A80	Queen's Pawn Game	1. d4	16
A40–A50	Slav Indian	1. d4 Nf6 2. c4 c6	2
A40	Zaire Defense	1. d4 Nc6 2. d5 Nb8 3. e4 Nf6 4. e5 Ng8	1
A41–A55	Old Indian Defense	1. d4 d6 2. c4	14
A41–A82	Rat Defense	1. d4 d6 2. c4 e5	4
A41	Robatsch Defense	1. d4 d6 2. Nf3 g6 3. c4 Bg7 4. e4 Bg4	1
A41	Wade Defense	1. d4 d6 2. Nf3 Bg4	1
A43–A52	Indian Defense	1. d4 Nf6	41
A45	Amazon Attack	1. d4 Nf6 2. Nc3 d5 3. Qd3	1
A45	Basque Opening	1. d4 Nf6 2. b3	1
A45	Canard Opening	1. d4 Nf6 2. f4	1
A45	Paleface Attack	1. d4 Nf6 2. f3	1
A45	Trompowsky Attack	1. d4 Nf6 2. Bg5	10
A46	Döry Defense	1. d4 Nf6 2. Nf3 Ne4	1
A46–A48	Torre Attack	1. d4 Nf6 2. Nf3 e6 3. Bg5	6
A46	Yusupov-Rubinstein System	1. d4 Nf6 2. Nf3 e6 3. e3	1
A47	Marienbad System	1. d4 Nf6 2. Nf3 b6 3. g3 Bb7 4. Bg2 c5	2
A47	Pseudo Queen's Indian Defense	1. d4 Nf6 2. Nf3 b6	2
A48	East Indian Defense	1. d4 Nf6 2. Nf3 g6	1
A48	London System	1. d4 Nf6 2. Nf3 g6 3. Bf4	7
A50	Mexican Defense	1. d4 Nf6 2. c4 Nc6	2
A50	Queen's Indian Accelerated	1. d4 Nf6 2. c4 b6	1
A56	Grünfeld Defense	1. d4 Nf6 2. c4 c5 3. e3 g6 4. Nc3 Bg7 …	1
A56	Vulture Defense	1. d4 Nf6 2. c4 c5 3. d5 Ne4	1
A57–A59	Benko Gambit	1. d4 Nf6 2. c4 c5 3. d5 b5	8
A57–A59	Benko Gambit Accepted	1. d4 Nf6 2. c4 c5 3. d5 b5 4. cxb5 a6	10
A57	Benko Gambit Declined	1. d4 Nf6 2. c4 c5 3. d5 b5 4. e4	6
A80–A99	Dutch Defense	1. d4 f5	69

B — Semi-open games 772 lines

ECO	Family	Defining moves	Lines
B00	Barnes Defense	1. e4 f6	1
B00	Borg Defense	1. e4 g5	4
B00	Carr Defense	1. e4 h6	2
B00	Duras Gambit	1. e4 f5	1
B00	Fried Fox Defense	1. e4 f6 2. d4 Kf7	1
B00	Goldsmith Defense	1. e4 h5	2
B00	Hippopotamus Defense	1. e4 Nh6	2
B00–B07	King's Pawn Game	1. e4	2
B00	Lemming Defense	1. e4 Na6	1
B00–B07	Lion Defense	1. e4 d6 2. d4 Nf6 3. f3	6
B00	Nimzowitsch Defense	1. e4 Nc6	43
B00	Owen Defense	1. e4 b6	8
B00–B09	Pirc Defense	1. e4 d6	28
B00–B06	Rat Defense	1. e4 d6 2. f4	6
B00	St. George Defense	1. e4 a6	4
B00–B01	Van Geet Opening	1. e4 d5 2. Nc3 dxe4 3. Nxe4 e5	2
B00	Ware Defense	1. e4 a5	2
B01	Scandinavian Defense	1. e4 d5	45
B02–B05	Alekhine Defense	1. e4 Nf6	56
B06–B27	Modern Defense	1. e4 g6	28
B06–B27	Pterodactyl Defense	1. d4 g6 2. e4 Bg7 3. Nc3 c5 4. d5	25
B07	Czech Defense	1. e4 d6 2. d4 Nf6 3. Nc3 c6	1
B10–B19	Caro-Kann Defense	1. e4 c6	110
B20–B99	Sicilian Defense	1. e4 c5	391
B21	Bird Opening	1. e4 c5 2. f4 d5 3. Nf3 dxe4	1

C — Open games & French 1250 lines

ECO	Family	Defining moves	Lines
C00–C19	French Defense	1. e4 e6	212
C00	Rat Defense	1. d4 e6 2. e4 d6	1
C20	Barnes Opening	1. f3 e5 2. e4 Nf6 3. Bc4	1
C20	Bongcloud Attack	1. e4 e5 2. Ke2	1
C20–C22	Center Game	1. e4 e5 2. d4	18
C20	English Opening	1. e4 e5 2. c4	1
C20–C44	King's Pawn Game	1. e4 e5	36
C20	King's Pawn Opening	1. e4 e5 2. b3	3
C20	Portuguese Opening	1. e4 e5 2. Bb5	3
C21	Center Game Accepted	1. e4 e5 2. d4 exd4	1
C21	Danish Gambit	1. e4 e5 2. d4 exd4 3. c3	1
C21	Danish Gambit Accepted	1. e4 e5 2. d4 exd4 3. c3 Ne7	6
C21	Danish Gambit Declined	1. e4 e5 2. d4 exd4 3. c3 d5	1
C23–C43	Bishop's Opening	1. e4 e5 2. Bc4	41
C25	Vienna Gambit	1. e4 e5 2. Nc3 Nc6 3. f4	15
C25–C29	Vienna Game	1. e4 e5 2. Nc3	41
C30	King's Gambit	1. e4 e5 2. f4	1
C30–C32	King's Gambit Declined	1. e4 c5 2. f4 e5	53
C31	Van Geet Opening	1. e4 e5 2. f4 d5 3. Nc3 dxe4 4. Nxe4	1
C33–C39	King's Gambit Accepted	1. e4 e5 2. f4 exf4	137
C40	Elephant Gambit	1. e4 e5 2. Nf3 d5	4
C40	Gunderam Defense	1. e4 e5 2. Nf3 Qe7	1
C40–C44	King's Knight Opening	1. e4 e5 2. Nf3	3
C40–C44	Latvian Gambit	1. e4 e5 2. Nf3 f5	17
C40	Latvian Gambit Accepted	1. e4 e5 2. Nf3 f5 3. exf5	9
C41	Philidor Defense	1. e4 e5 2. Nf3 d6	44
C42–C43	Petrov's Defense	1. e4 e5 2. Nf3 Nf6	50
C44	Dresden Opening	1. e4 e5 2. Nf3 Nc6 3. c4 Nf6 4. Nxe5	1
C44	Irish Gambit	1. e4 e5 2. Nf3 Nc6 3. Nxe5	1
C44	Ponziani Opening	1. e4 e5 2. Nf3 Nc6 3. c3	16
C44–C45	Scotch Game	1. e4 e5 2. Nf3 Nc6 3. d4	53
C46	Three Knights Opening	1. e4 e5 2. Nf3 Nc6 3. Nc3	6
C47–C50	Four Knights Game	1. e4 e5 2. Nf3 Nc6 3. Nc3 Nf6	49
C50–C59	Italian Game	1. e4 e5 2. Nf3 Nc6 3. Bc4	187
C60–C99	Ruy Lopez	1. e4 e5 2. Nf3 Nc6 3. Bb5	235

D — Closed & semi-closed 614 lines

ECO	Family	Defining moves	Lines
D00	Amazon Attack	1. d4 d5 2. Qd3	1
D00	Blackmar-Diemer Gambit	1. d4 d5 2. e4	18
D00	Blackmar-Diemer Gambit Accepted	1. d4 d5 2. e4 dxe4 3. Nc3 Nf6 4. f3 exf3	22
D00	Blackmar-Diemer Gambit Declined	1. d4 d5 2. e4 dxe4 3. Nc3 Nf6 4. f3 c5	9
D00–D05	Queen's Pawn Game	1. d4 d5	66
D01	Rapport-Jobava System	1. d4 d5 2. Nc3 e6 3. Bf4	4
D01	Richter-Veresov Attack	1. d4 Nf6 2. Nc3 d5 3. Bg5	8
D02	London System	1. d4 Nf6 2. Nf3 d5 3. Bf4 c5 4. e3 Qb6 …	1
D02–D69	Queen's Gambit Declined	1. d4 d5 2. c4 c5	198
D05	Rubinstein Opening	1. d4 Nf6 2. Nf3 e6 3. e3 c5 4. Bd3 d5 …	6
D06	Queen's Gambit	1. d4 d5 2. c4	1
D10–D19	Slav Defense	1. d4 d5 2. c4 c6	52
D20–D29	Queen's Gambit Accepted	1. d4 d5 2. c4 dxc4	58
D30–D49	Semi-Slav Defense	1. d4 d5 2. c4 e6 3. Nc3 c6	69
D32–D34	Tarrasch Defense	1. d4 d5 2. c4 e6 3. Nc3 c5	27
D44	Semi-Slav Defense Accepted	1. d4 d5 2. c4 c6 3. Nf3 Nf6 4. Nc3 e6 …	1
D70–D79	Neo-Grünfeld Defense	1. d4 Nf6 2. c4 g6 3. f3 d5	16
D80–D99	Grünfeld Defense	1. d4 Nf6 2. c4 g6 3. Nc3 d5	57

E — Indian defenses 357 lines

ECO	Family	Defining moves	Lines
E00–E09	Catalan Opening	1. d4 Nf6 2. c4 e6 3. g3	32
E00–E60	Indian Defense	1. d4 Nf6 2. c4 g6	12
E10	Blumenfeld Countergambit	1. d4 Nf6 2. c4 e6 3. Nf3 c5 4. d5 b5	3
E10	Blumenfeld Countergambit Accepted	1. d4 Nf6 2. c4 e6 3. Nf3 c5 4. d5 b5 …	1
E11	Bogo-Indian Defense	1. d4 Nf6 2. c4 e6 3. Nf3 Bb4+	21
E12–E19	Queen's Indian Defense	1. d4 Nf6 2. c4 e6 3. Nf3 b6	68
E20–E59	Nimzo-Indian Defense	1. d4 Nf6 2. c4 e6 3. Nc3 Bb4	99
E60	Grünfeld Defense	1. d4 Nf6 2. c4 g6 3. g3 Bg7 4. Bg2 d5	1
E60–E99	King's Indian Defense	1. d4 Nf6 2. c4 g6 3. g3	119
E60	Queen's Pawn	1. d4 Nf6 2. c4 g6 3. Qc2	1

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Family pages group related lines: the family head with a diagram, main continuations and every catalogued variation.

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