HAProxy is a free, very fast and reliable reverse-proxy offering high availability, load balancing, and proxying for TCP and HTTP-based applications. It is particularly suited for very high traffic web sites and powers a significant portion of the world's most visited ones. Over the years it has become the de-facto standard opensource load balancer, is now shipped with most mainstream Linux distributions, and is often deployed by default in cloud platforms. Since it does not advertise itself, we only know it's used when the admins report it :-)

The HAProxy core team maintains multiple versions in parallel. Since version 1.8, two major version are emitted every year. The first digit usually indicates a breaking change (config format etc) but in practice rarely changes. The second digit indicates new features. Both constitute a branch. One extra number appears after these digits to indicate the bug fix release.

Open Source Identity and Access Management

Add authentication to applications and secure services with minimum effort.
No need to deal with storing users or authenticating users.

Keycloak provides user federation, strong authentication, user management, fine-grained authorization, and more.

OpenID Connect is a simple identity layer built on top of the OAuth 2.0 protocol, which allows clients to verify the identity of an end user based on the authentication performed by an authorization server or identity provider (IdP), as well as to obtain basic profile information about the end user in an interoperable and REST-like manner. OpenID Connect specifies a RESTful HTTP API, using JSON as a data format.

OpenID Connect is an increasingly common authentication protocol: when an app prompts you to authenticate using your Facebook or Google+ credentials, the app is probably using OpenID Connect.

OpenID Connect allows a range of clients, including web-based, mobile, and JavaScript clients, to request and receive information about authenticated sessions and end-users.

OneLogin provides a custom connector option that makes it easy to configure your OpenID Connect-enabled app to use OneLogin as the Identity Provider (IdP) in an OpenID Connect flow.

For more information about API authorization, see How to setup an API Authorization PoC.