CAIN-42 CAIN StudioHow CAIN-42 compares · Policy & authorization
CAIN-42 vs OPA / Rego (Styra)
The Open Policy Agent is a general-purpose policy engine; Rego is its language. It is widely used as a policy decision point across cloud-native systems (CAIN-42 uses OPA/Rego internally).
What OPA / Rego (Styra) does well
- A mature, widely adopted policy engine.
- A large ecosystem of integrations and policy packs.
- Free and open source.
What CAIN-42 does differently
- Enforces at the tool-call boundary, before anything runs.
- Orders authorization through a Byzantine quorum (3-of-4): one "yes" is never enough.
- Leaves a per-action signed receipt you can verify offline with a clean-room verifier.
- Authority continuity: a change to the model, tool, memory, skill or delegation forces a re-check.
- Self-serve from $19.75/mo; runs hosted, self-hosted or air-gapped.
Capability difference
| Capability | CAIN-42 | OPA / Rego (Styra) | Source (verified 2026-10-14) |
|---|---|---|---|
| Primary focus | Runtime governance in the execution path | General-purpose policy decision engine | OPA source page verified 2026-10-14 |
| Policy that can only narrow authority | Yes (non-broadening compiler + differential) | Policy as authored; broadening is allowed | |
| Byzantine-ordered authorization (quorum cert) | Yes — 3-of-4 PBFT quorum certificate | Not in scope (a policy engine) | |
| Per-action signed receipt, offline-verifiable | Yes — Ed25519, hash-chained, offline-verifiable | Not in scope | |
| Agent-native concepts (lease, portfolio) | Yes | Not in scope | |
| Public entry price | $19.75/mo self-serve | Free / OSS |
When to pick which
Pick OPA/Rego as the policy engine (as CAIN-42 does). Pick CAIN-42 for the agent-native authority, enforcement and evidence wrapped around it.
Based on each vendor's public homepage and product pages, last reviewed 2026-10-14. No affiliation and no claim about their internals. "No*" means we found no public documentation of that capability, not that the vendor cannot do it.