Alfresco is easily the most comprehensive and extensible way to manage documents and other digital assets across enterprise repositories, thanks to integrations with the likes of SharePoint, Salesforce, Amazon S3, and Google Drive.
Additions in the latest release, like Smart Folders metadata, let you more easily search and access content without knowing its location. New tools like the Model Manager guide nontechnical users through tasks that used to require techs, such as shaping a consistent content repository.
Alfresco offers on-premises and cloud editions, as well as a hybrid sync option that facilitates content access and collaboration with entities beyond the firewall. With Alfresco Mobile, users gain on-the-go access, including full integration with Microsoft Office apps. Developers get a good, solid SDK to customize and extend the platform, a REST API for client apps, a Java API for server-side extensions -- lots of options.
A free community edition, a SaaS edition, and the enterprise-grade Alfresco One offer a number of ways to get started. Note the community edition has a number of limitations, including no support for HA clustering, hybrid cloud deployments, or extensions.
-- James R. Borck