LLMs - Cartesia Docs

Cartesia manages the model integration, so you do not need a provider account or API key.

Free LLM usage until October 1, 2026.

Choose an LLM

GET /v1/agents/models returns the models available to your account. Each entry includes its provider, average latency, and token prices. Set the model by ID:

{
  "config": {
    "model": { "id": "gpt-5.4-mini" }
  }
}

Changing the model creates a new agent version. You can easily switch models in the Playground or through the API to compare candidates.

Generation settings

config.model also accepts two optional settings. Set temperature to null to use the model’s default. Set max_output_tokens to null for no output-token limit.

temperature ranges from 0 to 1. Lower values produce more consistent responses; higher values produce more varied responses.
max_output_tokens limits the number of tokens in a response. It ranges from 1 to 4096.

{
  "config": {
    "model": {
      "id": "gpt-5.4-mini",
      "temperature": 0.3,
      "max_output_tokens": 1024
    }
  }
}

​Choose an LLM

​Generation settings

Choose an LLM

Generation settings