Free Server Saver

Give a memory-constrained server ways to reduce its workload as memory pressure rises.

Free Server Saver responds in stages, from slowing eligible distant mobs and limiting natural spawning to reducing view and simulation distances. You choose which interventions are allowed.

See what is happening

Use /fss status and /fss metrics to check the current state, or inspect recent lag spikes, entities, and chunks with the diagnostic commands. Settings are in serverconfig/freeserversaver-server.toml.

Choose the trade-off

Stronger interventions can change gameplay. The emergency tier can remove eligible distant mobs, and exception quarantine can remove repeatedly failing entities or block entities. Back up your world and review those options before enabling them. Protected mobs include named, tamed, and boss mobs where the relevant safeguards apply.

This release has not yet been validated on a live production server. Test it on a backup before using it on an active server.

This targets memory pressure; it is not a fix for every cause of lag or crashes. Check which modules are active when combining it with other performance or recovery mods.

Paid commissions for videos, streams and servers. Send me your idea: [email protected]

All Rights Reserved. Free to include in any modpack, on any platform, monetized or not, without permission or credit.

This is an unofficial community mod and is not affiliated with any hosting provider.

Source: https://github.com/KURONAMI333/free-server-saver

Bugs and questions: comment on the CurseForge page or DM @kuronami333 on X.

Watch JVM heap pressure and scale back expensive server work in stages before low-memory conditions become an emergency.

Free Server Saver targets slowdowns caused by high heap occupancy on low-memory servers. It does not fix network latency or every source of low TPS; its scope is the work it can reduce when measured heap pressure rises.

Adaptive throttling

After a 20-second startup warm-up, the mod checks heap use about every two seconds. Its default thresholds are:

Each tier is released after heap use falls five percentage points below its entry threshold, which prevents rapid switching near a boundary. Individual intervention modules can be disabled in serverconfig/freeserversaver-server.toml.

Protected activity

Bosses, named mobs, leashed or tamed mobs, and other persistent entities are excluded from destructive intervention. Combat, pathfinding, projectiles, visible timed states, and moving entities continue at full rate. Newly spawned entities receive a five-second grace period. Random ticks for crops, leaves, snow, and fire are not changed.

Operator tools

All /fss commands require permission level 2. Key commands include:

• /fss status and /fss metrics — show the current tier, heap use, player count, loaded chunks, and view distance.
• /fss history and /fss lagspikes — show recent tier changes and ticks longer than 100 ms.
• /fss top entities and /fss inspect chunks — help locate entity-heavy or heavily loaded areas.
• /fss storage and /fss prune — report world size and identify isolated loaded chunks. They do not delete world files.
• /fss pregen [radius] — generates chunks around the command source; it yields when Chunky is installed.
• /fss quarantine — lists entities or block entities removed after repeatedly throwing tick exceptions.

Metaspace monitoring, boot-time history, an idle-timer notice, and Discord alerts are also available. The Discord webhook, automatic threshold tuning, and mob-density scan are disabled by default.

Compatibility and limits

At startup, Free Server Saver disables specific overlapping modules when it detects supported performance or recovery mods. For example, it yields chunk pre-generation to Chunky and exception quarantine to Neruina, Bug Fix Mod, or Failsafe. The startup log records each disabled module.

The emergency tier can remove eligible distant mobs, and exception quarantine can remove faulty entity data after repeated failures. Back up the world before using these features. The current release has build and automated checks but has not yet been validated on a live production server.

Paid commissions for videos, streams and servers. Send me your idea: [email protected]

All Rights Reserved. Modpack inclusion is allowed without permission or credit. This is an unofficial community mod and is not affiliated with any hosting provider.

Bugs and questions: comment on the CurseForge page, or DM @kuronami333 on X.

Source