A server that runs 24/7 for a group that plays two evenings a week is mostly a machine burning money in an empty room. The obvious fix is to start the server only when someone actually wants to play. It is one of the most searched Minecraft hosting problems, and almost every answer you'll find is a DIY tool. This guide covers those tools honestly, and then the managed alternative for anyone who would rather not operate any of it.
What "starts when someone joins" actually requires
Minecraft clients don't send a magic wake packet. Something has to listen on the server's address around the clock, answer server-list pings so the server still looks alive, recognize a real join attempt, start the actual server process, and hand the connection over. That "something" is small, but it has to run 24/7 somewhere, which is exactly the thing you were trying to avoid paying for.
That is the honest core of this topic: wake-on-join moves the always-on burden from the big server process to a tiny listener. The question is who runs the listener.
Option 1: lazymc (self-hosted, the community favourite)
lazymc is a small Rust proxy that sits on your server's port. While the server sleeps it answers pings with a "sleeping" status, and when a player joins it boots the real server and forwards the connection. It's free, mature, and genuinely good.
Here is what you're signing up for: a machine of your own (a home box or a rented VPS) that stays online and patched, port forwarding or firewall care, a config file to maintain across server updates, and the role of the person who fixes it when the group wants to play and something is off. If you enjoy that kind of tinkering, lazymc is a fine answer.
Option 2: plugins and scripts
Spigot-family plugins like ServerAlarmClock, systemd socket activation, and scripts like mcstart all live in this space. A plugin can't start a stopped server, because the JVM it lives in is the thing that's off. These setups therefore pair a watcher process with a start script, which means more moving parts than lazymc and the same 24/7 machine requirement. They make sense mostly when you already run other services on the same box and know your way around a shell.
Option 3: managed wake-on-join
The third route is a host where sleep-and-wake is a feature rather than a project. On VoxelRun it's called wake-on-join: a per-server switch that lets a stopped server keep its hostname and port, stay visible in the server list with a sleeping message, and start automatically when a player connects. The other half of the loop is built in too. Idle auto-stop shuts the server down after a quiet period you choose, anywhere from 5 minutes to 24 hours.
Billing follows the loop. Compute is metered only while the server runs, with no rounding up to the hour, and the first 10 GB of storage are free, so a typical friends server literally costs nothing while it sleeps. Waking spends the owner's credits, which is why the feature is opt-in per server and can be tied to your whitelist: with the whitelist on, only listed players can trigger a start, and server-list scanners just see the sleeping message.
What the joining player experiences
This part is worth knowing on any setup, self-hosted or managed. A Minecraft client waits only about 30 seconds for a login before giving up. A vanilla or lightly modded server that boots in under half a minute can hold the join and let the player walk straight into the world. A heavy modpack that needs several minutes cannot. In that case the player gets a short disconnect message asking them to rejoin in a minute, and they get in on the second try. Any tool that promises instant joins for a 6 GB modpack is overpromising. The polished version of this experience is a clear message, not magic.
Choosing between them
Run lazymc if you already keep a machine online anyway and like operating things. Use plugins or scripts if the server shares a box with other services you manage. Pick managed wake-on-join if the whole point was to stop being the person responsible for an always-on machine. The listener, the idle stop, backups, and billing then become one switch in a panel.
Whichever way you go, close the loop. Waking on join without stopping on idle only automates the cheap half. It's the empty hours that cost money.