# Basic Usage

## Instantiating a Client for Optimization Work

### Without Environment Variables

Instantiate a `qci_client.QciClient` for QCi’s production server with your secret API token string as follows—

    # An alias for `from qci_client.optimization.client import OptimizationClient as QciClient`.
    from qci_client import QciClient

    client = QciClient(url="https://api.qci-prod.com", api_token="<secret_token>")

Warning

Be careful not to accidentally share your secret API token when sharing code.

### With Environment Variables

To access the API using environment variables, set the following—

- QCI_API_URL - URL string for the Qatalyst API. Example: “https://api.qci-prod.com”

- QCI_TOKEN - Secret API token string for securely accessing the Qatalyst API.

then instantiate a `qci_client.QciClient` as follows—

    # An alias for `from qci_client.optimization.client import OptimizationClient as QciClient`.
    from qci_client import QciClient

    client = QciClient()