Developers using LinkedIn APIs need to migrate to version 2.0 by March 1. Developers can use the LinkedIn APIs to integrate LinkedIn users' professional identities with third party services, and easily share content. Version 2 updates the APIs with more modern technologies, including OAuth 2.0 for authentication.
LinkedIn is also adding a number of options through its developer program on March 1. Sign In with LinkedIn allows LinkedIn users to login to third party apps with their LinkedIn credentials (similar to login with Google or Facebook). See the Sign In with LinkedIn docs for more details.
Share on LinkedIn allows users to share certain content and information with their network. This feature was available through version 1 of the API, but the format has changed. Check out the API docs for specifics.
In version 1, a number of APIs were used to manage company pages. In version 2, the APIs are consolidated into the LinkedIn Marketing Developer Program. Developers must participate in the Marketing Developer program for continued access to these features.