The Open Science Observatory presents a collection of indicators and visualizations that help interested stakeholders (policy makers and research administrators among others) better understand the Open Science landscape in Europe across countries. The platform assists the monitoring, and consequently the enhancing, of open science policy uptake across different dimensions of interest, revealing weak spots and hidden potential. Based on the OpenAIRE Research Graph, following open science principles and an evidence-based approach, the indicators can be used to provide timely and reliable insights on the evolution of open science in Europe and assist in promoting good practices. The Open Science Observatory is available at https://osobservatory.openaire.eu