The default mode for most applications of Cromwell, suitable for production use. Server mode starts Cromwell as a web server that exposes REST endpoints. All features and APIs are available.

By default the server will be accessible at http://localhost:8000. See the Server Section of the configuration for more information on how to configure it. A description of the endpoints can be found in the API Section.

Follow the Server Tutorial to get your Cromwell server up and running in a few steps.


A good way to get started with Cromwell and experiment quickly. Run mode launches a single workflow from the command line and exits 0 or 1 to indicate the result. Appropriate for prototyping or demo use on a user's local machine. Features are limited and the web API is not supported.

Sending a SIGINT signal (via CTRL-C for example) will by default abort all running jobs and then exit. This behavior can be configured, and is explained in more details in the Abort section of the configuration.