What is the difference between an AI gateway and a policy gateway?
An AI gateway routes and observes LLM traffic. A policy gateway enforces your custom content rules inline — rewrite, redact, escalate, or refuse — and logs every decision for audits.
Comparison
AI gateway vs moderation API vs guardrails vs policy gateway
AI gateway, moderation API, guardrails, and policy gateway sound similar but work at different layers and give you different levels of control. Most teams conflate them and end up with gaps in their safety stack.
This page compares all four so you can pick the right tool — or combination — for your governance requirements.
Definition of AI gateway vs moderation API vs guardrails vs policy gateway
An AI gateway routes and observes LLM traffic. A moderation API scores content for harm categories. Guardrails are provider-side content filters. A policy gateway enforces your custom rules inline with deterministic outcomes and audit logs.
Why AI gateway vs moderation API vs guardrails vs policy gateway matters
- Generic AI gateways (Kong, Portkey) route traffic but don't enforce content policy.
- Moderation APIs (OpenAI Moderation) return scores but don't block or rewrite — you must build enforcement yourself.
- Provider guardrails (Bedrock Guardrails, Vertex AI Safety) enforce the provider's rules, not yours.
- A policy gateway enforces your rules with deterministic outcomes and audit-ready decision metadata.
How it works
- Evaluate what you actually need: routing, scoring, provider-default filtering, or custom enforcement.
- If you need custom rules with audit logs, you need a policy gateway.
- If you only need traffic management, a generic AI gateway suffices.
- If you need both, layer a policy gateway on top of your routing layer.
Example
Comparison table
| Capability | Generic AI gateway | Moderation API | Provider guardrails | Policy Gateway |
|---|---|---|---|---|
| Traffic routing | Yes | No | No | Yes |
| Content scoring | Some | Yes | Yes | Yes |
| Inline enforcement | No | No — scores only | Yes — provider rules | Yes — your rules |
| Custom rules | Limited | No | No | Full policy-as-code |
| Rewrite / redact | No | No | Limited | Yes |
| Audit logs with decision metadata | Basic | No | Limited | Full structured logs |
| Shadow / canary rollout | No | No | No | Yes |
| SIEM export | Varies | No | Varies | Splunk, Datadog, Elastic, S3, Azure Monitor |
| Who controls the rules | Platform team | Provider | Provider | You |
FAQ
Frequently Asked Questions
Can I use a moderation API instead of a policy gateway?
A moderation API returns scores but does not enforce decisions. You must build the enforcement logic yourself. A policy gateway handles scoring and enforcement in one step.
Are provider guardrails enough for enterprise governance?
Usually not. Provider guardrails enforce the provider's rules, which are opaque and change without notice. Enterprise teams need control over what is allowed or refused.
Do I need all four?
Typically you need a routing layer (AI gateway) plus a policy enforcement layer (policy gateway). Moderation APIs and provider guardrails are optional complements, not replacements.