Warrant is a Zanzibar-inspired, policy-based authorization engine that offers precise control over access and provides a centralized approach to managing RBAC models. It supports self-service role and permission management, enabling users to customize roles and permissions using prebuilt pages with minimal coding. Casbin is another open-source solution that uses a CONF file based on the PERM metamodel to abstract access control logic, making it easy to switch between different authorization models by simply updating the conf file. Keycloak is an open-source identity and access management solution that handles authentication and authorization, providing a centralized solution for managing users, roles, permissions, and access control policies. Ory Keto is a Zanzibar-inspired authorization server for cloud-native applications, allowing you to create roles and assign permissions using its permission language. Permify provides an authorization language for modeling authorization policies for RBAC and other access control models, such as ABAC and ReBAC. Casdoor uses the Casbin authorization library to implement RBAC, providing granular access control for built-in objects and groups. Zitadel is a cloud-native open-source IAM platform that offers RBAC and other IAM functionalities, including delegated access for partner organizations and hierarchical structures. Cerbos offers a plug-and-play approach to integrate with existing systems, centralizing policy management and introducing definitions of context-aware roles. Permit-OPAL is an open-source authorization layer built on an Open Policy Agent (OPA) that helps manage and enforce policy-as-code, including RBAC policies. Fairwinds RBAC Manager is specifically designed to manage RBAC within Kubernetes clusters, offering a declarative approach to create and modify role bindings and service accounts. When selecting an RBAC open-source solution, consider factors like functionality, ease of integration, community support, cost, performance, and scalability.