Improving the adoption of Nature-based Solutions (NBS) requires learning from successes and failures. Knowledge derived from implemented cases helps to identify for instance drivers and barriers of NBS implementation, generates lessons learned, and supports their upscaling. Online data pools that catalogue information from NBS case studies may help scientists and practitioners to create this knowledge. The aim of this review is to assess the knowledge transfer potential of online data pools for implementing and upscaling NBS. For that, we compared 21 online data pools that report on NBS case studies in terms of topics, availability and quality of information on NBS. We found a high variability in quantity, type and quality of the information documented, hindering comparability and limiting knowledge transfer. Our results show that the most common knowledge provided was on actions undertaken on NBS, their outcomes, case study site descriptions, specific challenges and information on responsible entities and partners. Information on key attributes of NBS, such as on ecosystem processes and services as well as on governance and financing issues, was often omitted. The missing information however would be important for further comparative research to overcome implementation gaps for NBS. Based on the discussion of our findings we propose categories for a more efficient online data pool and give recommendations for further research on NBS.