Clover EFI bootloader is a bootloader designed to boot and install macOS on PC-compatible computers. It is an open source bootloader that provides a number of customization options for users who wish to install and run macOS on their own hardware. The Clover EFI bootloader app or website allows users to customize and configure their bootloader setup, including options for booting from a variety of operating systems, setting up a variety of hardware configurations, and adding additional drivers or kexts to the bootloader. The Clover EFI bootloader also includes a number of advanced features, such as support for Secure Boot, as well as various graphical user interface options. With the help of the Clover EFI bootloader, users can easily install, configure, and manage their macOS installation on their own hardware, without having to rely on third-party tools or services.
REFI discontinued. It has no longer been maintained since 2013. The author suggested visiting http://alternativeapp.info/software/refind/, a fork of the original program.
rEFInd
gummiboot
rEFIt
Discontinued In May 2015, gummiboot was fully integrated into systemd to form its systemd boot component that serves as a UEFI boot manager. Following this action, the gummiboot source code repository was emptied in July 2015. - https://en.wikipedia.org/wiki/Gummiboot_(software)