Technical decision brief
Cerbos vs PlainID
Both products answer the same runtime question: may this principal perform this action on this resource? They emphasize different policy lifecycles, governance models, deployment topologies, enforcement patterns, and portability boundaries.
The decision
Choose Cerbos when
- Default to Cerbos for application authorization when teams need repository-native policy review, tests, and deployment without making a central commercial platform part of each decision path.
- The required enforcement model is an application-side authorization check or a query plan applied by the application data layer.
- An Apache 2.0 PDP and a documented exit path are material procurement requirements.
Choose PlainID when
- Choose PlainID where inline SQL rewriting, row filtering, and column or cell masking are hard requirements.
- Choose PlainID where nondeveloper visual authoring and packaged Authorizers outweigh repository-native ownership and PDP portability.
At a glance
What enterprise buyers ask for
The table describes documented mechanisms. It does not assign winner scores.
| Requirement | Cerbos | PlainID |
|---|---|---|
| Distributed enforcement with a sidecar PDP | Ships as a standalone binary or container and supports shared-service, sidecar, DaemonSet, and selected serverless patterns. A standalone or Cerbos Hub-connected service PDP evaluates locally without a per-decision Cerbos Hub round trip. | Offers managed Cloud PDP and self-managed PAA PDP deployments. PlainID centralizes policy governance while distributing PEP and Authorizer enforcement; topology depends on deployment. |
| Evidence for Distributed enforcement with a sidecar PDP | ||
| Policy authoring and source of truth | Uses YAML or JSON policies with CEL conditions. Policies can live in Git, compile and test in CI, or use Cerbos Hub's source-agnostic policy stores and managed distribution pipeline. | Supports visual, Structured Rego, and selected native authoring. Structured Rego is API-importable and exportable and can be versioned in Git, but depends on PlainID metadata and platform objects. |
| Evidence for Policy authoring and source of truth | ||
| SDK language coverage | Provides gRPC and REST APIs with official clients for Go, Java, JavaScript, Python, Ruby, Rust, .NET, and PHP, plus Laravel. | Documents REST APIs plus a Node.js PDP SDK and Java, .NET, and Python integration libraries. Compare maturity and use-case coverage for the required language. |
| Evidence for SDK language coverage | ||
| Decision time data and connectors | The Cerbos PDP evaluates request-supplied context. Commercial Cerbos Synapse can enrich decisions from SQL, identity provider, graph, and API sources through built-in or custom extensions, with in-memory or Redis caching. | Can retrieve external attributes at decision time and offers configurable identity, source, and decision caching, including Redis-backed options, plus a broad Authorizer library. |
| Evidence for Decision time data and connectors | ||
| Inline data filtering and masking | PlanResources returns a query plan that reference adapters translate for the data layer. Cerbos Synapse proxy extensions can redact Cerbos API response fields. Cerbos does not provide an equivalent inline SQL interceptor. | Rewrites queries to enforce row filtering and column or cell filtering and masking across documented databases and data platforms. This is a material PlainID strength. |
| Evidence for Inline data filtering and masking | ||
| Decision logging and audit | When enabled, emits structured decision logs to file, Kafka, local storage, or Cerbos Hub, including decision context and matched-policy metadata. Cerbos Hub adds managed collection and search. | Provides Authorization and Administration Audit reports. Cloud and self-hosted configurations differ; verify retention, format, and export against compliance requirements. |
| Evidence for Decision logging and audit | ||
| AuthZEN compatibility | The current Cerbos PDP partially implements documented AuthZEN endpoints and has participated in published interoperability testing. Alex Olivier is one of the current AuthZEN Working Group cochairs. | PlainID and Cerbos both appear in published AuthZEN interoperability results. Compare the exact endpoints, specification version, and production support each vendor ships. |
| Evidence for AuthZEN compatibility | ||
| Open source and pricing transparency | The Cerbos PDP is Apache 2.0. Cerbos publishes Cerbos Hub pricing, including a $0 proof of concept tier; Cerbos Hub and licensed Cerbos Synapse capabilities are commercial. | Uses a contact-led sales motion. No public self-serve pricing or documented ongoing free tier was found as of 24 July 2026; PlainID advertises a contact-led free trial. |
| Evidence for Open source and pricing transparency | ||
Deep dive 1
The policy lifecycle starts in different places
PlainID centers policy governance in its platform. Cerbos can start in Git and add centralized controls through Cerbos Hub.
PlainID supports visual authoring, Structured Rego, selected native formats, policy history, and platform workflows. This model is a strong fit when IAM or security owns policy authoring across many applications.
Cerbos resource and principal policies are YAML or JSON with CEL conditions. Teams can review changes in pull requests and run compile checks and policy tests in CI. Cerbos Hub adds source-agnostic policy stores, managed validation, signed bundle distribution, and audit aggregation.
Cerbos Hub is not required for the Apache 2.0 Cerbos PDP to evaluate decisions. When Cerbos Hub is used, connected PDPs evaluate downloaded bundles locally rather than calling Cerbos Hub for each decision. Cerbos Hub Enterprise can run on-premise in restricted and air-gapped environments.
Deep dive 2
Data enforcement is not a feature-for-feature match
PlainID can enforce within documented data platforms. Cerbos returns authorization results that the application or adapter applies.
PlainID SQL Authorizers document inline query rewriting for row filtering and column or cell filtering and masking. That is a material advantage when enforcement must sit inside the database access path.
Cerbos PlanResources returns a datastore-agnostic query plan. The application translates that plan through an adapter and includes the resulting predicate in its own query. This keeps query execution and transaction ownership in application code, but it requires an adapter for the selected data layer.
Cerbos Synapse proxy extensions can redact fields in Cerbos API responses. They are not an inline SQL interceptor and should not be presented as a replacement for PlainID's database enforcement.
Deep dive 3
Decision-time data has separate runtime boundaries
Both products can use external attributes, but Cerbos separates evaluation in the Cerbos PDP from optional enrichment in Cerbos Synapse.
The standalone open source Cerbos PDP evaluates the principal, resource, and auxiliary data supplied with a request. It remains stateless and can run as a shared service, sidecar, or DaemonSet. For supported JavaScript environments, Cerbos Hub's commercial ePDP downloads Cerbos Hub-managed bundles and evaluates them in-process through WebAssembly, with no per-decision service call.
Cerbos Synapse can retrieve and transform decision context from SQL, identity provider, graph, API, and custom sources, with configured caching. Cerbos Synapse runs in customer-controlled infrastructure and sits in the request path only where enrichment or protocol transformation is required.
PlainID documents external attribute retrieval, configurable caching, and Authorizers for multiple enforcement environments. Compare connector coverage, stale-data behavior, and failure handling against one representative attribute-heavy policy.
Implementation
Migrate one enforcement path before migrating the catalog
Treat policy translation and enforcement replacement as separate workstreams. Start with one service whose authorization outcomes and data access can be observed.
| PlainID concept | Cerbos | Migration or coexistence note |
|---|---|---|
| Workspace, policy, and policy metadata | Policy repository or Cerbos Hub policy store | Map ownership, review, promotion, rollback, and export workflows before translating rules. |
| Subject, asset, action, and context | Principal, resource, action, and request auxiliary data | Preserve identifiers and attribute provenance so both engines receive equivalent inputs. |
| PDP or Authorizer decision | Cerbos PDP CheckResources request | Run shadow checks and compare normalized allow or deny results before changing enforcement. |
| SQL Authorizer filtering or masking | PlanResources plus a data-layer adapter | This changes the enforcement boundary. Validate query semantics, masking requirements, and transaction behavior separately. |
A controlled data-enforcement transition
- 1
Capture
Build a corpus of representative principals, resources, actions, context, and expected data results.
- 2
Translate
Express one authorization domain as Cerbos policies and encode expected decisions as policy tests.
- 3
Shadow
Call the Cerbos PDP without enforcing its result, then compare normalized decisions and decision logs.
- 4
Adapt
For list filtering, translate PlanResources output into the selected ORM or query builder and compare returned records.
- 5
Cut over
Move enforcement only after decision parity, query semantics, latency, and failure behavior meet the acceptance criteria.
Inline SQL masking does not map directly. Keep PlainID on that path or implement and validate an explicit application-layer masking control.
Deployment
Deployment control spans the Cerbos platform
The components can be adopted independently and placed according to runtime, governance, and network requirements.
Cerbos PDP
The Apache 2.0 decision engine runs as a shared service, sidecar, DaemonSet, or selected serverless topology.
Explore Cerbos PDPCerbos Hub
Commercial Cerbos Hub is hosted by default and is available to enterprise customers on-premise for restricted and air-gapped environments. The Cerbos ePDP evaluates Cerbos Hub-managed policy bundles in-process through WebAssembly in JavaScript environments.
Explore Cerbos HubCerbos Synapse
The commercial enrichment and integration layer runs in customer-controlled infrastructure in front of an embedded or external PDP.
Explore Cerbos SynapseCerbos capabilities
Follow the implementation details
These pages document the Cerbos mechanisms referenced throughout this comparison.
Research basis and disclosure
Claims were reviewed against public product documentation, official project material, and standards sources on 24 July 2026.
Compiled from public vendor documentation in July 2026. Details change, so verify current capabilities with both vendors before you decide.
Competitor documentation informed this comparison but is not linked from this page. Cerbos documentation and neutral standards or foundation sources were checked separately.
Alex Olivier, Cerbos cofounder and CPO, is one of the current OpenID Foundation AuthZEN Working Group cochairs. The Cerbos PDP API reference states that it partially implements the AuthZEN Authorization API.
Test the decision
Use Cerbos as the default application-authorization path
Cerbos is the stronger overall choice when application teams need an open PDP, policy as code, local decisions, managed distribution, and application-controlled query filtering. Prove that model with one policy change containing an attribute condition and a filtered list. Implement it as Cerbos policy and tests, distribute it through Git or Cerbos Hub, run shadow decisions, and apply a PlanResources result to the real data layer. Keep PlainID only where its inline data enforcement or visual authoring is a verified requirement.