Sensenet (edit)

https://www.sensenet.com/

Open Source Content Services Platform written in .NET

https://manhng.com/blog/serenity/ (Serenity Application Platform)

https://manhng.com/blog/sensenet/ (Sensenet ECM - Open Source Enterprise Content Management)

Sensenet Demo

http://62.28.197.236/

Sensenet ECM 

Open Source Enterprise Content Management (ECM)

Source Code:

https://github.com/SenseNet/sensenet/releases

https://github.com/SenseNet/awesome-sensenet

Documentation:

https://community.sensenet.com/

Tutorials:

https://community.sensenet.com/tutorials/

https://community.sensenet.com/docs/sensenet-components/

NuGet:

https://community.sensenet.com/docs/install-sn-from-nuget/

Core layer and admin UI

• Services: core layer, mother of all components, all other packages are optional.
• WebPages: admin UI and built-in building blocks for WebForms enthusiasts.

Feature packages

• Workspaces: Workspace-related items (content types and templates, workspace dashboards and views) for sensenet.
• Workflow: Windows Workflow Foundation (WWF 4.5) integration into sensenet.
• Notification: Email notification component for the sensenet platform.
• …and more!

Client SDKs

• JavaScript/TypeScript client: a client API that can be used either in the browser or a mobile app.
• .Net client: C# client API for tools and desktop applications.