An aggregated data set of chess opening names.

To generate dist/, install Python, then pip3 install chess and run make. Or select the latest workflow run and download build artifacts.

• Title case is used for opening names.
• Names are structured like Opening family: Variation, Subvariation, ..., e.g., Sicilian Defense: Najdorf Variation, English Attack.
• The suggested way to classify games is to play moves backwards until a named position is found. To make this work well with common transpositions, multiple entries for a single opening may be added.
• However, each name has a unique shortest line. If necessary, a distinguishing move is appended, e.g., King's Gambit Accepted: Schurig Gambit, with Bb5.

Improvements, additions and fixes are welcome. If you have concrete suggestions, please be bold and submit the proposed changes directly as pull requests!

The changes will be live on lichess.org after the next update of scalachess (no fixed schedule) and the opening explorer (daily).

As a collection of facts, this data set is in the public domain. Considerable effort was spent curating and cleaning the data. Insofar as that qualifies for copyright, the work is released under the CC0 Public Domain Dedication.