SpaceBukkit has been discontinued. Similar games include Crafty Controller, which is free and open source. Other options are MCSManager, Pufferpanel, Pyrodactyl and McMyAdmin. In total there are eight Server Management Tools like SpaceBukkit for Linux, Windows, Mac, self-hosting and the web.
Crafty is a wrapper for a Minecraft server which runs in the background. It has tons of features, including a slick AdminLTE-based GUI, auto-backups and console commands.
Free, Secure, Distributed, Modern Control Panel for Minecraft and Steam Game Servers.
PufferPanel is an open source game server management panel designed for both small networks and game server providers. PufferPanel supports Minecraft, Spigot, Sponge, Source Dedicated Servers, BungeeCord, PocketMine and much more.
pyrodactyl is the Pterodactyl-based game server panel that's faster, smaller, safer, and more accessible. It's the world's best Pterodactyl, powered by pyro.host. Runs on Windows!.
United States
McMyAdmin is a web interface and administration utility for Minecraft Survival Multiplayer (SMP) servers. It lets you monitor the servers status, chat with users, manage groups and permissions, schedule events, perform updates and more.
United Kingdom
MineOS CRUX is a specialized distribution with a specific goal: To provide the ultimate server solution for Minecraft and to provide a robust and extendible platform for server mods and related value-added functionality.
Sweden
EU