SUSTAINable Offshore Wind (SUSTAINOW) develops innovative, open-access tools for sustainable site identification and holistic design for Offshore Wind Farms (OWFs) across their entire life cycle with improved marine data accessibility. To achieve the European Green Deal and REPowerEU Plan, Europe aims for 300 GW offshore wind capacity by 2050. However, existing planning tools for floating and fixed-bottom OWFs face challenges due to data gaps and methodological shortcomings. SUSTAINOW addresses these gaps by developing three prototypes: 1. Cross-border marine data space targeted OWF - Improving data accessibility and compatibility. 2. Evidence-based OWF siting tool – Optimizing site selection for sustainability and feasibility. 3. Informed OWF project design tool – Supporting holistic design and planning by predicting and managing project impacts. SUSTAINOW builds on established decision-support tools such as Environmental Impact Assessment (EIA), Strategic Environmental Assessment (SEA), Life Cycle Assessment (LCA), Social Impact Assessment (SIA), and Cumulative Impact Assessment (CIA). These tools facilitate "de-risking" strategies for OWFs by incorporating environmental, social, and economic considerations into planning and implementation, ensuring regulatory compliance and sustainability. The North Sea serves as the primary development basin for pioneering prototypes and establishing strategic roadmaps for implementation across other European sea basins. The project is executed by a multidisciplinary consortium of 11 partners from 8 countries, including academic institutions, industry leaders, and impact assessment specialists. By incorporating a holistic sustainability approach—covering life cycle stages, integration of socio-environmental aspects with economic costs and life-cycle impacts, impact management, and floating and fixed-bottom OWF designs—SUSTAINOW ensures a transparent, inclusive, and efficient pathway for offshore wind energy expansion.