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Chess Opening Database - Shredder Chess

We made a tool that lets you search the lichess game database by chess concepts. Link in the comments : r/chess

Does the win/draw/loss rate from the opening database also apply to lower rated games? - Chess Forums

Learn Chess Openings with SCID Database

Spreadsheet Library - Chess: Openings Database

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Chess Database - Opening Master

Opening repertoire study with spaced repetition (+ database and game collections) - Chess Forums