---
title: Model Aliases
description: Map virtual model names to provider targets with per-tenant overrides and weighted routing.
---

Model aliases let clients use logical names like `"fast"` or `"smart"` instead of provider-specific model identifiers. This decouples your API surface from provider details.

## Creating Aliases

```go
import "github.com/xraph/nexus/model"

gw := nexus.New(
    nexus.WithAlias("fast", model.AliasTarget{
        Provider: "anthropic",
        Model:    "claude-3.5-haiku",
    }),
    nexus.WithAlias("smart", model.AliasTarget{
        Provider: "openai",
        Model:    "gpt-4o",
    }),
)
```

Clients request `model: "fast"` and Nexus resolves it to `anthropic/claude-3.5-haiku`.

## Weighted Routing

Distribute traffic across multiple targets:

```go
nexus.WithAlias("balanced",
    model.AliasTarget{Provider: "openai", Model: "gpt-4o-mini", Weight: 0.7},
    model.AliasTarget{Provider: "anthropic", Model: "claude-3.5-haiku", Weight: 0.3},
)
```

## Per-Tenant Overrides

Different tenants can resolve the same alias to different models:

```go
nexus.WithTenantAlias("premium-tenant", "fast",
    model.AliasTarget{Provider: "openai", Model: "gpt-4o"},
)
```

When `premium-tenant` requests `model: "fast"`, they get `gpt-4o` instead of the default `claude-3.5-haiku`.

## Alias Resolution

Alias resolution happens in the pipeline middleware chain (priority 250). The original model name is replaced with the resolved provider and model before routing.