The paper provides an overview of the literature on Circular Economy (CE) theoretical approaches, strategies and implementation cases. After analyzing different CE approaches and the underlying principles the paper then proceeds with the main goal of developing tools for CE implementation. Two tools are presented. The first is a CE Strategies Database, which includes 45 CE strategies that are applicable to different parts of the value chain. The second is a CE Implementation Database, which includes over 100 case studies categorized by Scope, Parts of the Value Chain that are involved, as well as by the used Strategy and Implementation Level. An analysis of the state of the art in CE implementation is also included in the paper. One of the observations from the analysis is that while such Parts of the Value Chain as Recovery/Recycling and Consumption/Use are prominently featured, others, including Manufacturing and Distribution, are rarely involved in CE. On the other hand, the Implementation Levels of the used Strategies indicate that many market-ready solutions exist already. The Scope of current CE implementation considers selected products, materials and sectors, while system changes to economy are rarely suggested. Finally, the CE monitoring methods and suggestions for future development are also discussed in this paper. The analysis of the theoretical approaches can serve as an introduction to CE concept, while the developed tools can be instrumental for designing new CE cases.