Apps with 'Authentication Proxy' feature

LemonlLDAP::NG is a modular Web-SSO based on Apache::Session modules. It simplifies the build of a protected area with a few changes in the application. It manages both authentication and authorization and provides headers for accounting.

Delivers continuous IT security monitoring, compliance assessment, vulnerability detection, asset discovery, and collaborative management across cloud and on-premises environments.

10Duke Identity Provider makes it easy for your customers to access and register to multiple applications with single username and password or using their favorite social login, secures profile data and easily integrates with leading business tools.

Apereo CAS - Enterprise Single Sign On for the Web.

Cntlm - Fast NTLM authentication proxy accelerator with tunneling, written in pure C