SimpleSAMLphp is a simple application written in native PHP that deals with authentication. SimpleSAMLphp supports several federation protocols, authentication mechanisms and can be used both for local authentication, as a service provider or as an identity provider. simpleSAMLphp can even be used to bridge other federation protocols, in example allowing you to setup a Shibboleth 1.3 Service Provider in a SAML 2.0 Federation (or the other way around).

Open source libraries in Java and C++ providing core message, binding, and profile classes for implementing applications based on SAML 1.0, 1.1, and 2.0. Extensive design integration with the native Java and C++ programming models is provided. OpenSAML is a low-level toolkit that does not by itself implement full SAML profiles such as single sign-on, but can be used to simplify the implementation of such profiles. Provided under the standard Apache 2.0 license for use in any commercial or non-commercial code.

A flexible and comprehensive open source, cross-domain, attribute-based web single-sign on system based on SAML 1.x and 2.0. Built on the OpenSAML libraries, a Java-based identity provider and native (C++) service provider are provided. The identity provider supports pluggability of both authentication and attribute sources and supports most of the core SAML SSO profiles and bindings. The service provider supports most popular web servers and enables seamless and loosely coupled integration of authentication and attribute data with applications without programming to product-specific APIs.

Lasso is a free software C library implementing the Liberty Alliance and SAML standards (ID-FF, SAMLv2, ID-WSF); it defines processes for federated identities, single sign-on and related protocols, and is used to bring digital identity features to web sites and applications. Lasso passed both ID-FF 1.2 and SAMLv2 Liberty interoperability tests.

Lasso comes with native language support for Java, Perl, Python and PHP.

LemonLDAP::NG is a full open source WebSSO product.

It supports a lot af authentication backends :

• LDAP
• SSL
• Kerberos
• CAS
• DBI
• Liberty Alliance
• SAMLv2
• OpenID
• Twitter

Nexus Argus Authentication Server  is a versatile, flexible and cost-efficient single sign-on access solution for web applications. The product name “Argus” refers to the mythological figure with one hundred eyes engaged by a goddess to guard a holy present. Analogously, Nexus Argus is the watcher of organizations’ valuable information accessible over the web. Nexus Argus combines best-of-breed security features with novel technologies for easy integration and user-friendliness:

OneLogin is a cloud-based provider of single sign-on, user provisioning and directory integration. OneLogin is pre-integrated with 1,500+ of applications, such as Salesforce, Google Apps, SugarCRM, WebEx, Workday, OpenAir, Box.net, Cornerstone OnDemand, Coupa, Yammer, Zendesk, WordPress, Central Desktop, KnowledgeTree and many more. 

The goal of OpenSSO is to provide an extensible implementation of an identity services infrastructure that will facilitate single sign-on for web applications hosted on web servers and application servers. Delivered as a self-contained J2EE application, OpenSSO provides access management, federation, and web services security functionality in a simple WAR file that

PingFederate is a standalone federated identity server utilizing SAML 1.0, 1.1 and 2.0 to enable secure single sign-on to Internet applications for employees, customers and business partners.

RSA Federated Identity Manager is a flexible, scalable, and widely deployed solution for identity federation. With RSA Federated Identity Manager, enterprises can share trusted user credentials securely and confidently.  This enables convenient access to multiple external applications or web services using a single identity and logon.  Whether collaborating with business partners, outsourced service providers, supply chain partners, or across multiple offices or agencies; federation provides a standard-based way to leverage trusted identities between organizations.