TICToK is a knowledgebase of chemicals found in tattoo inks, compiled from publicly available regulatory and scientific resources. The chemical classifications presented in this knowledgebase are derived from multiple publicly available resources and are provided solely for informational purposes, and they are neither authoritative nor binding. The authors bear no responsibility for any errors, omissions, or inconsistencies originating from these external sources. Users are advised to exercise independent judgment when interpreting chemical classifications and any other data provided in this resource. Importantly, our sole goal to build this resource on tattoo ink chemicals is to enable future basic research on this topic, and it does not necessarily reflect the views or objectives of our employers or funders.