Veto vs Alter
Alter and Veto both appear in the "AI agent security" category, but they solve fundamentally different problems. Alter is the auth layer for AI agents -- it manages who the agent is and what credentials it holds. Veto is the authorization layer -- it controls what the agent does with those credentials. Understanding this distinction is the whole comparison.
The core distinction
Alter answers: "Does this agent have valid credentials to access this API?" It manages OAuth tokens, issues ephemeral scope-narrowed credentials, and handles token rotation. Think of it as a credential vault with policy.
Veto answers: "Should this agent be allowed to make this specific tool call with these specific arguments?" It intercepts tool calls, evaluates them against policies, and routes sensitive actions to human approval. Think of it as a firewall between the agent's intent and execution.
An agent with valid OAuth credentials (Alter's domain) can still approve a $500K transaction it shouldn't (Veto's domain). These are different security layers.
Feature comparison
| Capability | Veto | Alter |
|---|---|---|
| Tool-call authorization | ||
| Declarative YAML policies | ||
| Human-in-the-loop approvals | Partial | |
| OAuth credential vaulting | ||
| Ephemeral token issuance | ||
| Token scope narrowing | ||
| RBAC / ABAC policies | ||
| Audit trails | ||
| Open source SDK | ||
| Self-hosted option | ||
| MCP gateway | Partial | |
| Framework integrations (LangChain, etc.) | ||
| Embeddable OAuth widget | ||
| 100+ provider connectors | ||
| Local / offline mode |
Where each excels
Alter's strength: credential lifecycle
Alter's best feature is something Veto doesn't attempt. When your agent needs to call the Salesforce API, Alter issues a seconds-lived, scope-narrowed OAuth token for exactly that request. The token expires immediately after use. No long-lived API keys sitting in env files, no over-scoped service accounts, no token rotation scripts.
This is genuinely valuable. Credential sprawl is one of the most common security problems in agent systems. If your primary pain point is "our agents have too many API keys with too many permissions and we can't rotate them fast enough," Alter solves that directly.
Alter also provides an embeddable OAuth widget and 100+ provider connectors, which significantly reduces the integration work for teams connecting agents to external services.
Veto's strength: action-level control
Veto operates at a different layer. Even with perfectly scoped credentials, an agent can still make bad decisions. A claims processing agent with valid database credentials can approve a $500,000 settlement when the authority limit is $50,000. A customer service agent with valid CRM access can read medical records to answer a billing question.
Veto intercepts the tool call itself -- the function name, the arguments, the context -- and evaluates it against declarative policies before execution. It doesn't manage credentials; it governs what happens after authentication succeeds.
The SDK is open source (Apache-2.0), policies are YAML files in your repo, and the policy engine runs locally in your process. No vendor dependency for the core authorization logic.
The security layer model
Think of agent security as a stack. Each layer addresses a different threat:
Layer 3: Action authorization
Should this agent make this specific tool call with these arguments?
Layer 2: Credential management
Does this agent have valid, minimally-scoped credentials for this API?
Layer 1: Authentication
Is this agent who it claims to be?
These layers are complementary. You can use Alter to manage credentials and Veto to authorize actions. Or you can use either independently. The question is which layer addresses your primary security concern.
Pricing
Open source SDK is free (Apache-2.0). Managed cloud starts free with usage-based tiers. Self-host the SDK and API server for $0 if you prefer. No per-agent or per-seat pricing.
Early access / enterprise pricing. As a YC S25 startup, pricing is likely still being established. Contact their team at alterai.dev for current rates. Expect usage-based or per-connection pricing typical of credential management platforms.
Decision framework
Choose Veto when
- Your primary risk is agents taking wrong actions, not credential leakage
- You need human approval workflows for sensitive operations
- You want an open source solution you can inspect, fork, or self-host
- You need declarative policies that live in version control
- You already handle your own authentication / OAuth
Choose Alter when
- Your primary risk is credential sprawl and over-scoped API keys
- You need ephemeral, scope-narrowed OAuth tokens per request
- You're connecting agents to many third-party services (100+ connectors)
- You want managed credential lifecycle (rotation, expiry, revocation)
- You need an embeddable OAuth widget for end-user connections
Frequently asked questions
Can I use Veto and Alter together?
Doesn't Alter's fine-grained RBAC do the same thing as Veto's policies?
Which is faster to integrate?
Is Alter open source?
Control what your agents do, not just who they are.