Migrating from Aserto? Evaluating the Alternatives

With the news that Aserto is shutting down its SaaS platform on May 31, 2025, many teams are now faced with an urgent and unsettling challenge: choosing a new authorization provider. If you’re one of them, you’re likely asking:

What’s a reliable alternative that won’t force me to rebuild everything from scratch—or worse, disappear next year?

These transitions can be tough. It’s a reminder that authorization isn’t just a feature—it’s infrastructure. And like any core infrastructure choice, you need something that’s dependable, well-supported, and designed to scale with your product.

That’s where Oso comes in.

We’ve helped teams migrate from other authorization solutions before and know where the common pain points are. In this post, we’ll walk through how Aserto compares to Oso, what makes Oso the best long-term Authorization as a Service platform, and offer practical tips to help your team modernize your authorization stack with confidence.

Summary of What We’ll Cover

• Key criteria for evaluating authorization solutions
• Aserto alternatives: feature and architecture comparison
• Why Oso stands out for developers and security teams
• Migration tips: how to move from Aserto to Oso with confidence

Evaluating Authorization Solutions: What Matters Most?

When choosing an authorization platform, you need more than a feature checklist. The best solutions deliver:

• Low latency: Authorization checks must be fast, ideally under 10 ms, to avoid slowing down your application.
• Flexible models: Support for RBAC (role-based access control), ABAC (attribute-based access control), and ReBAC (relationship-based access control) is essential for modern apps.
• Seamless integration: The solution should work with your existing databases and infrastructure.
• Deterministic and testable: You need to know exactly how permissions are evaluated, with tools for debugging and testing policies.
• Developer experience: Clear APIs, expressive policy languages, and strong documentation make a big difference in adoption and maintenance.

Imagine a SaaS platform with thousands of users and complex team hierarchies. If authorization checks are slow or inconsistent, user experience and security both suffer.

Aserto Alternatives

What Aserto Users Should Consider In Their Next Authorization Solution 

Aserto worked by centralizing authorization data in Postgres, syncing policy and directory data to edge nodes, and evaluating requests via a local BoltDB-based key-value store. This made it performant for reads, but brittle and limited when it came to:

• Complex modeling (e.g., resource-specific roles, nested groups)
• Real-time consistency
• Data filtering that reflects policy logic
• Developer experience and tooling

Many teams also found themselves stuck between two models: either use Aserto’s graph-based directory, or write policies in OPA/Rego—but not both in a truly integrated way. This made certain use cases, like negation or cross-object filtering, difficult or outright impossible.

These are some conversations from their Community Slack: 

Q: In Aserto, you can’t do “check” operations in a bulk request, right?

A: This is currently not possible, the OpenID AuthZen specification is trying to define one which we will adopt as soon as it is in DRAFT mode.

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Q: Is there any way to get the audit logs to know who changed the objects/relationships of the directory? 

A: Currently this is not built-in, we are considering this as a part of moving towards an event stream based model.

Feature and Architecture Comparison

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Key takeaways:

• Oso is one of the only cloud-based solutions offering local authorization without requiring data syncing, which means you get consistent, low-latency checks even for high-cardinality or rapidly changing data.
• Oso’s Polar language is expressive and easy to learn, letting you write concise rules for complex scenarios.
• Oso provides a deterministic framework, so you always know how permissions are evaluated and can test policies before deploying.

If you want to deepen your understanding on the technical comparison, read the comparison post: Aserto vs Oso

For teams considering Topaz, Aserto’s open source authorization engine, it’s worth noting that while the maintainers have committed to continued community support, the future of the project is less certain without a backing company. Open source can be a great option—but only if it’s actively maintained and supported. With Aserto winding down its SaaS platform, many teams are rightfully asking what long-term support, roadmap stability, and enterprise readiness will look like for Topaz going forward. And even if the project continues to receive strong community support, adopting it means taking on the full burden and administrative overhead of deploying, operating, and maintaining the service in a production-ready way—ensuring uptime, scaling, and performance falls entirely on your team. If your team needs a solution with guaranteed uptime, built-in testing, and commercial support you can count on, Oso offers a fully managed path forward.

Why Oso? Unique Value for Developers and Security Teams

Oso was built for teams who want to own their authorization logic without reinventing the wheel. We give developers a complete, production-ready authorization solution without forcing tradeoffs between policy logic, data modeling, or performance.

Here’s what sets Oso apart:

Local Authorization, No Syncing Required

Oso can perform authorization checks directly within your application, so there’s no need to sync data to a remote service. This approach delivers:

• Consistent, sub-10 ms response times
• No risk of stale permissions due to sync lag
• Full control over data residency and privacy

Performance at Scale

Aserto:

• Relies on syncing a local cache (BoltDB) from a Postgres-backed system
• “Edge” nodes still depend on 1-minute sync intervals or slower
• Issues reported with bulk authorization and unbound queries

Oso:

• Evaluates authorization operations in single-digit milliseconds
• 99.99% uptime SLA, with globally replicated edge nodes
• Designed to handle large-scale list filtering and complex decision trees with no drop in speed

Need to authorize thousands of actions per second? Oso is architected for scale from day one.

Flexible, Expressive Policy Language

With Oso’s Polar language, you can define rules like:

allow(user, "read", resource) if
 	has_role(user, "admin", resource);

This rule says: allow a user to read a resource if they have the admin role for that resource. You can extend this to support multi-tenancy, team hierarchies, or custom attributes with just a few lines.

Unified Policy + Data

Aserto splits the world between the policy layer (OPA) and the directory graph (data). This leads to limitations, like:

• No way to apply policy logic during list filtering
• Can’t express "negative" logic (e.g., user is banned) during graph traversal
• Inconsistent evaluation paths depending on the API used (Authorizer vs Directory)

With Oso, your policy and data are unified—so the same logic used for authorize() also powers list filtering, tests, and audits.

You get consistency and confidence at every level of your system.

Deployment Flexibility

Oso runs anywhere: cloud, hybrid, or on-premises (coming soon). You can use Oso as a managed service or deploy it in your VPC, giving you maximum flexibility.

Developer Experience

Aserto:

• Limited documentation and SDK support
• Hard to tell what’s possible or how to implement features
• Rego’s steep learning curve makes policies hard to write and debug

Oso:

• Rich developer tooling: Visual Rules Workbench, Explain mode, CLI, and robust SDKs
• Easy-to-read Polar language built for real-world authorization
• Dedicated guides for every major pattern: RBAC, ReBAC, ABAC, and custom roles

You’ll be able to write and test policies confidently—and fast.

Testable and Debuggable

Oso includes built-in policy tests, so you can catch issues before they reach production. This is especially valuable for teams with complex, evolving permission requirements.

Modeling Complex Authorization Logic

Aserto:

• No support for nested groups
• Challenging to implement resource-specific roles
• Must choose between graph data or policy logic—can’t combine them cleanly

Oso:

• First-class support for nested groups, resource hierarchies, and custom roles
  Express your logic in a single place using Polar, Oso’s purpose-built policy language
• Model both relationships and logic together in one consistent, testable framework

With Oso, you don’t have to contort your model to fit the tool—we built it to fit your app.

Migration Tips: Moving from Aserto to Oso

You don’t have to start from scratch—Oso’s architecture makes it straightforward to migrate your:

• User-directory relationships
• Role definitions
• Directory-based data models
• Rego logic (converted into Polar rules)

Switching authorization providers can feel daunting, but with the right approach, you can minimize risk and downtime. Our team has helped many teams through this exact process, and we’re here to help you go live in weeks—not months. Here's a step-by-step migration plan:

1. ‍Audit your current authorization model

• List all permission rules, roles, and resource types in your Aserto setup
• Identify any custom logic or edge cases
  

2. Map Aserto policies to Oso’s Polar language

• Translate rules into Polar syntax
• Use Oso’s policy tests to validate your logic
  

3. Integrate Oso with your application

• Replace Aserto API calls with Oso’s API or library functions
• Run integration tests to confirm everything behaves as expected
  

4. Run in parallel (shadow mode)

• Operate both Aserto and Oso side by side
• Log and compare authorization decisions to catch discrepancies
• Ensure the systems achieve parity
  

5. Cut over and monitor

• Fully switch to Oso once confident
• Monitor logs and metrics for any unexpected behavior
  This phased approach ensures a smooth transition with minimal disruption.

Conclusion: Why Oso is the Best Alternative

Authorization is too important to leave to chance. The right solution should give you speed, flexibility, and confidence without locking you into a single deployment model or forcing you to sync sensitive data. Oso stands out by offering local, testable authorization with support for RBAC, ABAC, and ReBAC, all backed by a developer-friendly API and policy language.

If you’re considering a move from Aserto or another provider, Oso’s migration path is clear and well-supported. You can start small, test policies in isolation, and scale up as your needs grow.

Ready to modernize your authorization? Connect with a real team of engineers ready to support your migration. 

You can also explore Oso’s documentation, try out the Polar language, and see how easy it is to build secure, scalable permission systems for your applications.