Oso Cloud

Judgement

What it is

Building block

What it does

Hosted authorization service where apps define permissions in the Polar policy language and query it for access decisions, now also aimed at AI agents.

Adopt it when

Your app has outgrown hand-coded role checks and needs relationship- or attribute-based permissions.

Watch out

Polar is a niche language, and the company's focus is shifting toward AI agent security.

Ready for

Usable

Runs as

Cloud service and library

Built with

Polar

What the license allows

Closed source: you use it under the maker's terms and cannot change or resell the code.

Judged on 2026-11-03 from the maker's description and Wikipedia. The license and age lines are worked out directly.

Open-source alternatives to Oso Cloud

1. 1
   Casbin apache

   Apache Casbin: an authorization library that supports access control models like ACL, RBAC, ABAC.

   Building block Production-ready Your application needs configurable permission rules without writing an authorisation engine.

   ★ 20k Apache-2.0 Go Active, pushed today
2. 2
   OPA open-policy-agent

   Open Policy Agent (OPA) is an open source, general-purpose policy engine.

   Building block Production-ready You want one policy language across Kubernetes, CI, APIs and infrastructure, with policies kept outside application code.

   ★ 12k Apache-2.0 Go Active, pushed today
3. 3
   SpiceDB authzed

   Open Source, Google Zanzibar-inspired database for scalably storing and querying fine-grained authorization data

   Building block Production-ready Your app needs fine-grained, relationship-based permissions such as sharing, teams and nested folders across services.

   ★ 7.2k Apache-2.0 Go Active, pushed yesterday
4. 4
   CASL stalniy

   CASL is an isomorphic authorization JavaScript library which restricts what resources a given user is allowed to access

   Building block Production-ready You need the same permission rules in front end and back end of a JavaScript app.

   ★ 7.1k MIT TypeScript Active, pushed today
5. 5
   OpenFGA openfga

   A high-performance and flexible authorization/permission engine built for developers and inspired by Google Zanzibar.

   Building block Production-ready You need fine-grained permissions as a separate service and want a vendor-neutral, CNCF-governed option.

   ★ 6.1k Apache-2.0 Go Active, pushed today
6. 6
   Permify Permify

   An open-source authorization as a service inspired by Google Zanzibar, designed to build and manage fine-grained and scalable authorization systems for any application. — Permify is now part of FusionAuth 🎉

   Building block Usable You want a fine-grained permission service with a readable schema and testing tools.

   ★ 6k AGPL-3.0 Go Active, pushed yesterday
7. 7
   Keto ory

   The most scalable and customizable permission server on the market. Fix your slow or broken permission system with Google's proven "Zanzibar" approach. Supports ACL, RBAC, and more. Written in Go, cloud native, headless, API-first. Available as a service on Ory Network and for self-hosters.

   Building block Usable You already use Ory Kratos or Hydra and want permissions from the same stack.

   ★ 5.4k Apache-2.0 Go Active, pushed 2 months ago
8. 8
   Cerbos cerbos

   Cerbos is an open-core authorization management platform for authorizing every identity and governing every action across applications, gateways, workloads, and AI agents.

   Building block Production-ready You want authorization rules out of application code but do not want to sync relationship data into another database.

   ★ 4.6k Apache-2.0 Go Active, pushed today
9. 9
   Topaz aserto-dev

   Cloud-native authorization for modern applications and APIs

   Building block Usable You want OPA-based policies plus relationship data in one local authorizer.

   ★ 1.4k Apache-2.0 Go Active, pushed 3 days ago
10. 10
    Warrant warrant-dev

    Warrant is a highly scalable, centralized authorization service based on Google Zanzibar. Use it to define, enforce, query, and audit application authorization and access control.

    Building block Usable Only if you already run it; new projects are better served by SpiceDB or OpenFGA.

    ★ 1.3k Apache-2.0 Go Slowing, pushed 11 months ago

Other commercial authorization and permission engines

1. 1
   AuthZed Cloud AuthZed

   Remove authorization bottlenecks, empower your team to innovate and expand with best-in-class performance at any scale.

   Building block Production-ready A product needs Google Docs-style sharing permissions at scale and the team is ready to adopt a relationship model.

   Commercial
2. 2
   Styra DAS Styra

   Complete system Usable A platform team runs OPA in many places and wants central policy management and impact analysis.

   Commercial

Under it

Every program, Oso Cloud included, runs on a microchip.

How compilers were built, back to punched paper tape