Routing Rules | AI Router

Use CEL-based routing rules to redirect AI Router requests to different models based on request attributes, evaluated in priority order.

Feature available with the Enterprise Plan

Routing Rules are CEL-based conditions that intercept requests to the AI Router and redirect them to a different model when matched. Rules are evaluated in priority order and the first matching rule wins. No further rules are evaluated after a match.

Use cases

Routing rules are most useful when you need to redirect or distribute traffic at the router level based on request attributes, without modifying any calling application.

Swap the model for a support bot without changing any code

Intercepts support bot requests addressed to one model and silently redirects them to a cheaper one, so the calling application needs no changes to benefit from the cost saving.

Send simple and complex documents to different models

Two rules at the same priority split document traffic by complexity: simple documents go to a lighter model, complex ones go to a more capable model, all based on metadata attached to each request.

Keep file attachment requests on models that support them

Matches requests that include a file attachment and routes them through an ordered list of models that all support native file input, so the request succeeds even if the first model is unavailable.

Automatically reroute traffic when a provider goes down

A low-priority catch-all rule that redirects traffic to an alternative set of models whenever primary providers are unavailable, keeping requests flowing without manual intervention.

Spread load evenly across multiple endpoints for the same model

Distributes requests in round-robin mode across multiple endpoints serving the same model, balancing inference load across providers without any changes required on the caller side.

How routing rules work

When a request arrives at the AI Router, the router evaluates all active routing rules in ascending priority order. The first rule whose CEL expression matches the request determines the target model. If no rule matches, the model from the original request payload is used.

Example: A request arrives with model: "openai/gpt-4o". A routing rule with condition model.contains("gpt-4o") and target openai/gpt-4o-mini is the highest-priority matching rule. The router redirects the request to gpt-4o-mini, regardless of what the caller specified. In CEL expressions, model refers to the model value from the request payload.

See also: Request-level load balancing

To distribute traffic across providers at the request level without organization-wide rules, use the load_balancer parameter directly in your API calls.

Visibility

• Global rules: visible to workspace administrators only.
• Project rules: visible to all members of the scoped project.

Creating a routing rule

From the Routing Rules list, click Add New Rule. A panel opens on the right with the following fields.

General

Field	Description
Rule Name	A display name for the routing rule.
Description	Optional context for administrators.
Enable Rule	Toggle to activate or deactivate the rule. When enabled, the rule is active and applied to matching requests.

Providers and traffic weight

Defines the target model or models to route matching requests to. This section is identical to the model configuration in Policies.

Models sets the distribution strategy for the target:

• Fallback: Route to the primary model. If it fails, try the next in the list.
• Weighted: Split traffic across models by percentage weights.
• Round Robin: Rotate evenly across all configured models.

Click Add to add a target model.

Priority

A numeric value that sets the evaluation order for this rule. Rules are evaluated in ascending order: priority 0 is evaluated before priority 10. The first matching rule wins.

Rule Builder

The Rule Builder constructs the CEL expression that determines whether this rule applies to a given request. Conditions are built from values present in the request headers and body.

Clicking Add opens a dropdown with the following condition types:

Condition	Description
Header	Match on a request header name and value.
Model	Match on the model specified in the request payload.
Identity	Match on the identity making the request.
Metadata	Match on metadata attached to the request.
Project	Match on the project scope of the request.

You can also click Add group to nest conditions into a logical group. Multiple conditions within a group are joined with and. Groups themselves can be joined with either and or or. Select the operator between groups to control how they combine. Each condition can be removed with .

The generated CEL expression is shown read-only in the CEL Expression Preview below the builder.