This free version of Structurizr allows you to view/edit diagrams, view documentation, and view architecture decision records defined in a single DSL or JSON workspace. Structurizr Lite can be used standalone for workspace viewing/authoring, or in conjunction with the cloud service/on-premises installation as an authoring/testing/staging environment.

Structurizr Lite - diagrams
Structurizr Lite - documentation
Structurizr Lite - architecture decision records

Structurizr Lite will look for a workspace.dsl and workspace.json file in a given directory, in that order, and use the file it finds first. If you change this file (e.g. via your text editor or one of the Structurizr client libraries), you can refresh your web browser to immediately see the changes.