IriusRisk is a threat modeling platform with dedicated capabilities for Operational Technology (OT) environments. It enables security teams to identify and address architectural security flaws in OT infrastructure during the design phase, before systems are built or deployed. The platform supports compliance with industrial security standards, including IEC/ANSI 62443, which is used for Industrial Control Systems (ICS) and OT assets classified as Critical National Infrastructure (CNI). It maps security requirements to specific Security Levels (SL) and shows corresponding countermeasures when components move between levels. IriusRisk incorporates the MITRE EMB3D™ threat model, which is designed for embedded devices. This content is mapped to IEC 62443 and includes three mitigation levels: Foundational, Intermediate, and Leading. The platform also includes the MITRE ATT&CK for Industrial Control Systems matrix, providing threats derived from techniques and sub-techniques, mitigations, data sources, and detections. The platform supports Infrastructure as Code (IaC) descriptors and integration with issue trackers to help scale and automate threat modeling outputs. It provides diagram-based interfaces for building threat models, applying standards, monitoring threats, generating countermeasures, and producing reports. IriusRisk is a technical member of the ISA Security Compliance Institute.