SpiceDB is an excellent Zanzibar. WardenAuth is ReBAC + RBAC + a platform.
SpiceDB by AuthZed is the most mature open-source Zanzibar implementation, with a managed cloud offering. It's purpose-built for relationship-based access control. But it only handles ReBAC — for RBAC, ABAC, audit trails, and API key management, you need additional tools. WardenAuth provides managed ReBAC alongside RBAC, ABAC, audit, and multi-tenancy — all from one API.
Overview
SpiceDB is the reference open-source Zanzibar implementation. It supports the full Zanzibar API surface — Check, Expand, Lookup, Watch — with a schema language for namespace configuration and a gRPC/HTTP API. AuthZed provides a managed cloud version.
But SpiceDB (and AuthZed) focus exclusively on relationship-based access control. If you also need RBAC (role-permission assignments), ABAC (attribute conditions), audit trails, or API key management, you need separate tools or must build them yourself. WardenAuth provides all of these alongside managed ReBAC in a single platform.
SpiceDB (AuthZed) — Strengths
- Most mature open-source Zanzibar (Apache 2.0)
- Full Zanzibar API: Check, Expand, Lookup, Watch
- Schema language for namespace configuration
- gRPC and HTTP APIs
- Managed cloud option (AuthZed)
- Active community and development
SpiceDB (AuthZed) — Limitations
- ReBAC only — no RBAC, ABAC, or role management
- Must learn SpiceDB schema language
- No audit trail beyond relationship changes
- No API key management
- No multi-tenancy primitives
- No SoD, approvals, or SCIM
- AuthZed managed pricing is custom/enterprise
Pricing comparison
| Scenario | SpiceDB (AuthZed) | WardenAuth |
|---|---|---|
| Open-source | Free (self-hosted, Apache 2.0) | Free (50K checks, managed) |
| Managed cloud | Custom (AuthZed) | $79/mo (Starter, 1M checks) |
| RBAC + audit + API keys | Must build or buy separately | Included at every tier |
Feature comparison
| Feature | SpiceDB (AuthZed) | WardenAuth |
|---|---|---|
| Relationship tuples (ReBAC) | ||
| Zanzibar Check/Expand/Lookup | ||
| Watch API (real-time updates) | ||
| Fine-grained RBAC | ||
| ABAC / attribute conditions | ||
| Built-in management dashboard | ||
| Audit trail (40+ events) | ||
| API key management | ||
| Multi-tenant scopes | ||
| SoD / Approval workflows | ||
| Webhooks | ||
| SSO / SCIM | Included (Business+) | |
| Flat-rate pricing | Free (OSS) | |
| Open-source (Apache 2.0) |
Use case guide
Choose SpiceDB if you need a dedicated, pure Zanzibar implementation — especially if you already have RBAC handled elsewhere, want the open-source option (Apache 2.0), or need the full Zanzibar API surface (Watch API, subject set queries).
Choose WardenAuth if you need ReBAC alongside RBAC, ABAC, audit, and multi-tenancy in a single platform. WardenAuth's relationship tuples provide the core Zanzibar use cases (ownership, sharing, hierarchy) without requiring a separate system or schema language.
SpiceDB is the best choice if you need a dedicated, pure Zanzibar implementation — especially if you value the open-source model and need the full API surface. But for teams that need ReBAC alongside RBAC, ABAC, audit, and multi-tenancy in a single platform, WardenAuth eliminates the need to run and integrate multiple authorization systems.
See for yourself — no credit card required.