Smart Router

The smart router classifies each request's complexity and routes it to the most appropriate model based on a routing profile you specify. This saves cost on simple requests while ensuring complex ones get capable models.

The router is pure rule-based logic with no external calls. Classification takes under 1 microsecond.

How to use it

Set model to a routing profile name instead of a specific model ID:

{
  "model": "auto",
  "messages": [{"role": "user", "content": "Explain recursion."}]
}

You can also use model aliases as shortcuts to specific models:

Complexity tiers

The router classifies each request into one of four tiers based on a weighted score:

The 15 scoring dimensions

The scorer analyzes user message content across 15 weighted dimensions. Higher score = more complex request.

The weights sum to 1.0. The weighted sum produces a score that maps to a complexity tier.

Routing table

Each (Profile, Tier) pair maps to a specific model:

Example: same prompt, different profiles

Prompt: "Hello!"
Tier: Simple (short, matches simple indicator keywords)

  eco     → deepseek/deepseek-chat       ($0.28/M input)
  auto    → google/gemini-2.5-flash      ($0.30/M input)
  premium → openai/gpt-4o                ($2.50/M input)

Prompt: "Prove step by step that quicksort has O(n log n) average complexity.
         Analyze edge cases and compare with mergesort."
Tier: Reasoning (reasoning markers: "prove", "step by step", "analyze", "compare")

  eco     → deepseek/deepseek-reasoner   ($0.28/M input)
  auto    → xai/grok-4-fast-reasoning    ($0.20/M input)
  premium → openai/o3                    ($2.00/M input)

Bypassing the router

To use a specific model, pass its full ID directly:

{
  "model": "anthropic/claude-opus-4-20250514",
  "messages": [...]
}

Or use a short alias:

{
  "model": "opus",
  "messages": [...]
}

See GET /v1/models for the full list of model IDs.