The Low Carbon Cities Evaluation Toolkit, a collaborative project between CityNet and Kookmin University Low Carbon Green Growth Research Center, offers cities a comprehensive approach to assess their progress in achieving low carbon status. Leveraging city-fed data, this flexible toolkit employs a unique indexing system adaptable to various variables. The primary objective of the toolkit was to craft the most practical and composite indices delineating the essential domains necessary for attaining low carbon cities. The city of Seoul and its 25 wards were selected as the pilots for the toolkit.