- Model ID: Found in the Baseten dashboard or returned when you deploy.
- API key: Authenticates your requests.
- Model input: A JSON body that matches the input expected by your model.
Authentication
The predict endpoint lives on your model’s own subdomain:Authorization header:
Request
predict.py
Baseten also accepts the legacy
Authorization: Api-Key <api_key> scheme on every endpoint, so existing scripts continue to work:Request
Predict API endpoints
Baseten provides two predict endpoints:/predict: Standard synchronous inference./async_predict: Asynchronous inference for long-running tasks.
Sync API endpoints
Custom servers also provide async endpoint that forwards requests to routes exposed by your server:
URL
https://model-{model_id}.../sync/health->/healthhttps://model-{model_id}.../sync/items->/itemshttps://model-{model_id}.../sync/items/123->/items/123
OpenAI SDK
Engine-Builder deployments expose an OpenAI-compatible server. To use an OpenAI SDK, set its base URL to your Baseten deployment and authenticate with your Baseten API key:openai_client.py
External LLM gateways
OpenAI-compatible LLM gateways, such as LiteLLM or OpenRouter, can route traffic to a Baseten deployment. Configure the gateway with three values:- Base URL:
https://model-{model_id}.api.baseten.co/environments/production/sync/v1, using the model ID for your deployment. Choose API endpoint on the model page in the Baseten dashboard to copy the full URL. - Model name: The value of
--served-model-namefrom your deployment’sstart_command. See the vLLM example for where this is set. When a single gateway routes to several deployments, use anorg/modelnaming convention (for example,acme/llama-3-70b) to keep routing unambiguous. - API key: A Baseten API key with access to the deployment.
{base_url}/chat/completions with model set to the served model name and an Authorization: Bearer <key> header.
Alternative invocation methods
- Baseten CLI:
baseten model predict - Model Dashboard: “Playground” button in the Baseten UI