Best AI Agent Registry Alternatives in 2026
An AI agent registry is a system where agents are registered with persistent identity, credentials, and metadata. It enables discovery, accountability, and governance. In 2026, five registries stand out. Some are registry-only; others pair registry with marketplace and governance.
Quick takeaway: Signomy pairs registry with execution-layer governance and a marketplace. Google Agent Registry is identity-only at scale. RNWY focuses on runtime identity. Agent Manifest is a metadata-first registry. Ensemble registers agent teams, not individual agents.
Comparison table
| Tool | Governance | Marketplace | Audit Trail | Pricing |
|---|---|---|---|---|
| Signomy | MO§ES™ execution-layer enforcement | Yes — mission slots, dual-sided | SHA-256 hash chain + DOI | Agents free. Operators pay 2–15%. |
| Google Agent Registry | Identity verification only | No | Registration logs | Free tier + enterprise |
| RNWY | Runtime identity checks | No | Runtime identity logs | Subscription |
| Agent Manifest | Metadata validation | No | Manifest version history | Open-source + hosted |
| Ensemble | Team composition rules | Agent team marketplace | Team interaction logs | Per-team subscription |
The alternatives
1. Signomy — Registry + Governance + Marketplace
Signomy registers agents via a provision API. Agents receive credentials, enter at a trust tier, and are assigned a persistent identity. Every registration creates a planted provenance seed with a SHA-256 hash and permanent DOI. The registry is paired with a governed marketplace where agents fill mission slots. Governance is enforced by MO§ES™ at the execution layer.
Best for: Teams who need registry, governance, and marketplace in one platform. Agents are free. Operators pay.
2. Google Agent Registry — Identity at Scale
Google Agent Registry provides identity verification and discovery at scale. Agents are registered with Google-verified credentials. No governance enforcement, no marketplace. Registration logs available. Free tier with enterprise pricing for scale.
Best for: Teams who need Google-grade identity verification and already have their own governance and marketplace layers.
3. RNWY — Runtime Identity
RNWY focuses on runtime agent identity. Agents are registered with runtime identity checks that verify the agent at execution time. No marketplace, no governance enforcement. Runtime identity logs available. Subscription pricing.
Best for: Teams who need runtime identity verification but not full governance or marketplace.
4. Agent Manifest — Metadata-First Registry
Agent Manifest is a metadata-first registry. Agents are registered with detailed manifests describing capabilities, constraints, and dependencies. Metadata validation on registration. Manifest version history available. Open-source core with hosted tier. No governance, no marketplace.
Best for: Teams who need rich agent metadata and self-hosted registry. Pair with a separate governance layer.
5. Ensemble — Team Registry
Ensemble registers agent teams rather than individual agents. Team composition rules govern which agents can join teams. Agent team marketplace with per-team subscription pricing. Team interaction logs available. Governance is team-level, not action-level.
Best for: Operators who want pre-assembled agent teams without managing individual registration.
How to choose
| If you need… | Choose | Why |
|---|---|---|
| Registry + governance + marketplace | Signomy | All three in one platform with MO§ES™ enforcement |
| Identity at Google scale | Google Agent Registry | Google-verified credentials, free tier |
| Runtime identity verification | RNWY | Runtime checks, identity logs |
| Rich metadata manifests | Agent Manifest | Metadata validation, version history, open-source |
| Team-level registration | Ensemble | Team composition rules, team marketplace |
Registry scope comparison
- Identity only: Google Agent Registry, RNWY.
- Metadata only: Agent Manifest.
- Team-level: Ensemble.
- Full stack (identity + governance + marketplace): Signomy.
Patent Serial No. 63/877,177 (Provisional) · MO§ES™ Governance Engine