Sakai Plus is an LTI 1.3 / LTI Advantage "tool provider" built in to Sakai.
The Plus Admin tool allows you to access the setup information needed to install Sakai as an LTI tool in your enterprise learning management system.
Sakai Plus lets you install Sakai as an LTI tool in any LMS that supports LTI Advantage, such as Canvas, Brightspace, Blackboard, Moodle, etc. Once installed, the instructors and students have a link in their Enterprise LMS to launch Sakai Plus in a new tab. In that new tab, they simply teach using any and all Sakai features. In the background, Sakai Plus keeps the rosters and grade books synchronized.
The teachers and students continue to use the Enterprise LMS to see grades, get notifications, view their calendar and due dates. This means that essential student records are stored in the Enterprise LMS as the system of record. Teachers can use as much or as little of Sakai Plus as they like in their teaching. Perhaps they want to use a few of Sakai's tools like Lessons, Tests and Quizzes, or Conversations. Or perhaps they are teaching a course where there are enhanced concerns around the control and possession of private student activity data - so they teach the entire course in Sakai Plus on a server owned by the school. Or perhaps a few faculty members want to use Sakai and make suggestions on how to improve the product and be part of an open source community that will listen to, care about, and implement their suggestions in a future version.
Sakai Plus has many hosting options. Sakai Plus is just a feature in every instance of Sakai 23 or later waiting to be enabled, configured and used. Sakai Plus is multi-tenant and efficient so it is possible to provide a free or low cost cloud service that would allow a school to test Sakai Plus or run a small pilot. You can get a small single-tenant vendor supported cloud instance of Sakai Plus from a Sakai Commercial Affiliate at about the cost of an LTI tool. Sakai can be self-hosted by a school using an Amazon EC2 Instance, an Aurora Serverless Database, and Amazon's Elastic File System (EFS). If a school is a little uncertain about their in-house cloud hosting skills, Sakai Commercial Affiliates can assist a school in setting up, monitoring and upgrading their Sakai Plus instance.