Potential users of Safe and Sustainable by Design (SSbD) approaches, in particular small and medium sized enterprises, struggle to find their way in the sheer amount of existing knowledge, testing methods and tools. To better guide them in making decisions throughout their entire design process of advanced nanomaterials, a user-friendly online intelligent SSbD Decision Support System (DSS) is developed within the HARMLESS project. Previous experience and stakeholder analysis is used to integrate existing as well as numerous newly generated NAM-based data & models and integrated approaches to testing and assessment (IATAs) into a unified HARMLESS SSbD framework. We propose a modular approach in which all data, knowledge and models are captured in stand-alone, interconnected FAIR components. HARMLESS will A) use eNanoMapper as a database to store experimental data, B) launch a new FAIR Data Point to capture all knowledge and decision rules, C) launch a novel Model FAIRpoint with runnable algorithms and D) launch a new Decision Support System interface. The DSS interface connects to the HARMLESS FAIR components, but can also connect to external components (e.g. NanoCommons Data Warehouse, Jaqpot, NanoInformaTIX). The decision support process is based on a well-established concept of Risk Informed Decision Making adopted by NASA and US NRC, based on the fusion of deterministic and probabilistic risk assessment. To this end, Bayesian network modelling is used to integrate existing and new knowledge, data and models into an integrative reasoning model that captures uncertainty. This information is presented in an interactive visualization presenting an overview of all important decision criteria augmented with SSbD advice allowing the user to interactively work with the tool to improve their design. Oral presentation, by Wouter Fransmann (TNO), at the nanoSAFE 2023 Conference (5-9.06.2023, Grenoble, France) on 6th June 2023 - Session: Methods, Tools, & Technologies for SSbD Purposes