RBAC vs. FGA: What's the difference and how do they work together?

Managing access to data is critical in complex environments with diverse applications and users. Traditional Role-Based Access Control (RBAC) works well in many cases, but as systems grow more dynamic, you may need more precise control.

Fine-Grained Authorization (FGA) provides a flexible, detailed approach to access management that complements RBAC.

In this article, we’ll compare FGA and RBAC, clarify their differences, and explain when to use them individually or together.

RBAC vs FGA: What are they?

Role-Based Access Control (RBAC)

RBAC is an access control model where permissions are grouped into roles rather than being assigned directly to users. Users are then assigned to these roles, simplifying permission management.

For example, a “Manager” role might have permissions to approve expenses, while an “Employee” role can only submit expenses. By bundling permissions into roles, RBAC enables centralized access control and easy onboarding—assigning a role automatically grants users the permissions they need.

RBAC operates on the principle of least privilege, ensuring users only receive permissions necessary for their roles. This simplicity makes RBAC ideal for environments with well-defined, static roles. However, in dynamic environments, RBAC can lead to role explosion—an unwieldy proliferation of narrowly scoped roles to meet specific needs.

Fine-Grained Authorization (FGA)

FGA is a pattern for implementing access control with high specificity. Instead of relying solely on roles, FGA evaluates access decisions based on various attributes, such as user identity, resource properties, contextual data (e.g., time or location), and even relationships between entities.

For instance, in a healthcare system, FGA might allow:

• Doctors to access an edit only their assigned patients' medical records.
• Nurses to update vitals but restrict access to sensitive billing information
• Billing staff to manage payments without viewing clinical data
  

Unlike RBAC, FGA enables dynamic, context-aware authorization decisions. This flexibility makes it ideal for systems requiring granular, attribute-based policies that evolve over time.

Key Differences Between RBAC and FGA

RBAC excels in providing a baseline for broad access, while FGA offers granularity for scenarios where roles alone are insufficient.

FGA vs. ABAC: Understanding the Distinction

While FGA and Attribute-Based Access Control (ABAC) appear similar, they serve different purposes:

ABAC is a formalized model that determines access by evaluating rules against user, resource, and environmental attributes. For example, ABAC might grant access to documents only during business hours and from within the company network.

FGA is an implementation pattern that can incorporate ABAC principles, relationship-based models (like Zanzibar), or custom logic.

FGA’s flexibility lies in its ability to use multiple models, including ABAC, for granular decision-making.

Using RBAC and FGA Together

RBAC and FGA are not mutually exclusive. Combining them allows you to leverage their strengths:

RBAC provides a baseline for broad access control through predefined roles.

FGA refines those permissions with granular, context-aware policies.

For example, in an enterprise SaaS application:

Use RBAC to assign broad access: A “Sales Manager” role might have general access to CRM data.

Layer FGA to define specific rules: Sales Managers can view only accounts in their region and during active business hours.

This hybrid approach balances simplicity and precision, ensuring scalable and manageable access control.

Other Access Control Models to Consider

Attribute-Based Access Control (ABAC)

Relies on attributes of the user, resource, and environment to determine access. Useful for dynamic, context-aware access.

Mandatory Access Control (MAC)

A strict, centralized model based on security labels. Often used in highly sensitive environments like government systems.

Discretionary Access Control (DAC)

Gives data owners control over access to their resources. Common in file systems where users set permissions for files or directories.

Relationship-Based Access Control (ReBAC)

Focuses on relationships between entities, as seen in Zanzibar-style systems. Particularly suited for social networks and collaborative platforms.

Performance Considerations

RBAC: Faster for coarse-grained decisions since it only checks role assignments.

FGA: Performance depends on implementation. Systems like WorkOS FGA or Google Zanzibar optimize for scale by precomputing relationships or using caching to speed up policy evaluation.

Getting started with WorkOS FGA

WorkOS FGA offers a plug-and-play Zanzibar-like service, delivering the same scalability, consistency, and performance — without any infrastructure to deploy and maintain.

We’ve built WorkOS FGA to help teams of all sizes solve various use cases: a seed-stage startup building a Google Docs-like collaborative application, an AI-startup looking to implement fine-grained permissions for a RAG application, a platform team at a large enterprise looking to adopt FGA as part of the transition from monolith to microservices.

FGA works with your existing WorkOS account and environments. Check out the developer docs and dashboard to get started.

When you’re ready to ship an authorization model to production, use one of the FGA SDKs to create/delete warrants and check/query user permissions directly from your application.