Auto Router

Set model to auto and OhMyGPT picks a model for each request from what the latest user message asks for: a fast, low-cost model for short, simple turns, a capable general model for most work, and a frontier model when the turn asks for proofs, algorithms, architecture or debugging. ohmygpt/auto and OpenRouter's openrouter/auto work the same way.

curl https://api.ohmygpt.com/v1/chat/completions \
  -H "Authorization: Bearer $OHMYGPT_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "auto",
    "messages": [{"role": "user", "content": "hi"}]
  }'

The response's model names the model that answered:

{
  "model": "deepseek/deepseek-v4.1-flash-1017",
  "choices": [{"message": {"role": "assistant", "content": "Hi! How can I help you today?"}}]
}

You pay that model's standard price; the router adds no fee. Auto works on Chat Completions, Responses and Messages, streaming or not. Endpoints that don't generate chat replies, such as Embeddings, reject it with 400 unsupported_endpoint.

ConversationsCopy Anchor Link

Send prompt_cache_key and the conversation stays on one model, so its prompt cache keeps working. Within a conversation the router can move up to a stronger model when a later turn is harder, and never moves back down:

Without prompt_cache_key, each request is routed on its own.

OptionsCopy Anchor Link

Add an auto-router entry to plugins, as on OpenRouter:

{
  "model": "auto",
  "plugins": [{
    "id": "auto-router",
    "allowed_models": ["openai/*", "google/*"],
    "excluded_models": ["openai/gpt-5.4-nano"],
    "cost_tier": "low"
  }],
  "messages": [{"role": "user", "content": "explain why the sky is blue"}]
}

A cost_tier other than these, or lists that leave no model, return 400 invalid_parameter naming the field. The auto-router entry is not sent on to the model.