Relationship-Based Access Control (ReBAC) has emerged as a crucial model for managing permissions in complex and interconnected systems, with OpenFGA and Permit.io being two prominent implementations of this approach. OpenFGA, initially developed by Okta, is an open-source, self-hosted solution that implements the Zanzibar model, emphasizing fine-grained control through a code-first approach, though it requires developers to maintain their infrastructure. Permit.io, on the other hand, offers a managed ReBAC service with added support for Attribute-Based Access Control (ABAC), providing an intuitive no-code Policy Editor UI, Terraform integration, and a comprehensive suite of tools to streamline policy management and operational simplicity. While OpenFGA is suited for those seeking an open-source solution with complete control over their infrastructure, Permit.io caters to teams that prioritize ease of use and quick deployment, combining ReBAC and ABAC capabilities without the need for extensive infrastructure management. Each platform offers distinct advantages depending on a team's specific needs, with OpenFGA providing a robust core engine and Permit.io delivering a full-featured authorization platform.