Alternatives to systemd
This page lists available Init systems as alternative to systemd
Init is the first process started during system boot. It is a a daemon process that continues running until the system is shut down. Init is the direct or indirect ancestor of all other processes, and automatically adopts all orphaned processes. It is started by the kernel using a hard-coded filename; if the kernel is unable to start it, panic will result. Init is typically assigned process identifier 1.
The init scripts (or rc) are launched by the init process to guarantee basic functionality on system start and shutdown. This includes (un)mounting of file systems and launching of daemons. A service manager takes this one step further by providing active control over launched processes, or process supervision. An example is to monitor for crashes and restart processes accordingly.
These components combine to the init system. Some inits include the service manager in the init process, or have init scripts in close relation to them. These inits are below referred to as integrated, though entries in different categories may explicitely depend on each other.
Alternatives to systemd
|uselessd||A fork of systemd v208. This project is dead.||2014-11-16|
|Upstart||Event-based init system which handles starting, stopping and supervising of tasks and services. This project is dead.||2014-09-04|
|initng||Dependency-based init system with parallelization and asynchronous start.||2007-11-11|
|Epoch||Single-threaded init system designed for minimal footprint, compatibility and unified configuration.||2015-06-23|
|finit||Fast and extensible init, originally based on EeePC fastinit.||2015-10-16|
|nosh||A suite of system-level utilities for initializing and running a BSD or Linux system, for managing daemons, for managing terminals, and for managing logging.||2015-10-31|
|runit||UNIX init scheme with service supervision, a replacement for SysVinit, and other init schemes.||2014-08-10|
- SysVinit - Traditional System V init. 
- ninit - Fork from minit 
- sinit - Simple init initially based on Rich Felker’s minimal init.
- uinit - Smallest init possible. 
- busybox init - BusyBox init. 
- daemontools - Collection of tools for managing UNIX services.
- Monit - Monit is a process supervision tool for Unix and Linux. With monit, system status can be viewed directly from the command line, or via the native HTTP(S) web server.
- OpenRC - Dependency-based rc system that works with the system-provided init, normally SysVinit.
- perp - Persistent process (service) supervisor and managment framework for UNIX.
- s6 - Small suite of programs for UNIX, designed to allow service supervision in the line of daemontools and runit.
- watchman - A not-so-simple service manager for Linux. 
- System XVI - Modular, self-healing, and interface-oriented service manager and init system.