LLM Gateway

Expanded Definition

An LLM Gateway is a policy-enforcing control plane for model traffic, placing one governed interface between applications and multiple model providers. It typically handles routing, request normalization, quotas, logging, prompt filtering, and provider fallback, so teams can manage usage without embedding provider-specific logic across the stack. In practice, it is closer to an identity and governance boundary than a simple API proxy.

Usage in the industry is still evolving. Some vendors present gateways as cost-management layers, while others treat them as security controls for data loss prevention, auditability, and model access governance. In NHI programs, the gateway becomes especially important because it mediates which workload, agent, or service account is allowed to invoke which model, with what payload, and under what policy. That maps closely to guidance in the OWASP Top 10 for Agentic Applications 2026 and the NIST AI Risk Management Framework.

The most common misapplication is treating the gateway as a thin routing layer, which occurs when organisations skip authorization, content controls, and logging because they assume the downstream model provider already covers governance.

Examples and Use Cases

Implementing an LLM Gateway rigorously often introduces latency and policy complexity, requiring organisations to weigh centralised control against developer convenience and request performance.

• A bank routes employee chat requests through a gateway that blocks sensitive account data, logs prompts for audit, and sends only approved requests to public and private models.
• An AI product team uses the gateway to enforce model-specific quotas, retry logic, and fallback selection across OpenAI, Anthropic, and open-weight models without rewriting the application layer.
• An enterprise agent platform binds each agent’s non-human identity to gateway policy, limiting which tools, models, and data classifications that agent may access.
• A security team uses the gateway to inspect outbound prompts and responses for secrets exposure, helping reduce risk highlighted in NHIMG research such as the DeepSeek breach and the AI LLM hijack breach.
• A platform architect applies gateway policy to separate production, testing, and high-risk workloads, aligning usage with the NIST AI 600-1 Generative AI Profile.

NHIMG coverage of the OWASP NHI Top 10 and the LiteLLM PyPI package breach shows why gateway controls matter when model access is distributed across many applications and environments.

Why It Matters in NHI Security

An LLM Gateway matters because it creates a single enforcement point for the credentials, policies, and telemetry that govern model use. Without that layer, service accounts, API keys, and agent permissions proliferate across applications, making it harder to prove who invoked which model, with what data, and under which authority. That is a classic NHI weakness: the control gap is not the model itself, but the identities and secrets that unlock it.

This is where gateway governance intersects directly with secret exposure and misuse. NHIMG research on AI credential abuse shows how quickly exposed credentials can be weaponised, and the same pattern applies when gateway credentials are weakly managed or broadly shared. In the SailPoint report on AI agents, 80% of organisations said their agents had already performed actions beyond intended scope, while only 52% could track and audit the data those agents accessed. Those numbers underline why gateway logging and policy enforcement are not optional extras.

Practitioners should also align gateway design with the CSA MAESTRO agentic AI threat modeling framework and the NIST AI Risk Management Framework so policy, identity, and telemetry stay tied together. Organisations typically encounter gateway requirements only after a model misuse incident, at which point the gateway becomes operationally unavoidable to address.

Related resources from NHI Mgmt Group

• How should security teams use LLM-based identity risk scoring in production?
• How should security teams govern partner API access at the gateway?
• What is the difference between a managed gateway and a reverse proxy in front of a gateway?
• Why do LLM jailbreaks create an IAM problem?