COL is a data container used by Capture One application. COL files were used by older versions of Capture One for storing photo collections. User can add any photos from their library to COL file.

Capture One is a paid software available in two licensing models: perpetual and subscription-based. Newer versions of Capture One replaced COL format with COSESSIONDB which fulfills the same role. Capture One is a professional photo database managment tool.