// modpack server guide
Tools for builders server hosting & setup guide
A Tools for builders server needs Java 21 and about 2–3.5 GB of RAM for up to 15 players.
This Mod Pack Gives You Almost ALL Building Essencials, Like Litematica for building from shematics! Theres Also More! With Some ResourcePacks That I Picked As the Dont Change A Lot And Just Make The Game Look Better!
Summary from Tools for builders on Modrinth.
Tools for builders is a Fabric modpack for Minecraft 1.21.1 with 41 mods, 14 of which run on the server. We'd pick our Standard plan (4 GB) for it.
Quick facts
| Loader | Fabric |
|---|---|
| Minecraft versions | 1.21.1 |
| Java needed | Java 21 for Minecraft 1.21.1 Java version chart. |
| Mods | 14 run on the server41 in the pack. The other 27 are client-only, and the server skips them. |
| RAM | About 2 GB for 1–3 playersBy player count. |
| Downloads | 111,115 on Modrinth |
| Last updated | August 17, 2026 (version 1.0.4) |
| First published | September 18, 2024 on Modrinth |
| Server support | Required: the pack has mods that must run on the server. |
| Server pack | Not published separatelyHow to build the server. |
| Modrinth tags | lightweight, optimization, technology, magic |
Tools for builders server files
No. Tools for builders has no separate server pack on Modrinth, so the server is built from the .mrpack: the Fabric server for Minecraft 1.21.1, plus the pack's overrides folder and the server-side mods its modrinth.index.json lists. A modpack installer does this for you; our guide shows how to make a server for a modpack with no server pack.
How much RAM does a Tools for builders server need?
| Players online | RAM | DSN plan |
|---|---|---|
| 1–3 players | About 2 GB | Standard (4 GB) |
| 4–8 players | About 2–2.5 GB | Standard (4 GB) |
| 9–15 players | About 2–3.5 GB | Standard (4 GB) |
Estimated from 14 mods on the server with our RAM calculator, not measured: low end if players stay together, high end if they spread out.
Set Java's heap (-Xmx) 10–15% under the RAM you have, about -Xmx3500M on 4 GB. Fabric 1.21.1 takes it in the java command (-Xmx), usually in the start script. RAM guide.
Tools for builders server requirements
| Java | Java 21 |
|---|---|
| Loader | Fabric for Minecraft 1.21.1 |
| CPU | Fast single-core speed (one main thread). |
| RAM | About 2–3.5 GB for 1–15 players (table above) |
| Disk | The server files, a growing world and backups |
| Network | TCP port 25565 open to players |
Recommended plan
Our pick for Tools for builders
Standard
4 GB RAM · planned launch price $16/month
At about 14 Fabric mods this is a light pack, so 4 GB of RAM covers it for a small group.
Ordering is closed until we relaunch. We aren't taking orders or payments while we move to new hardware. Join the launch list and we'll email you when Standard servers open.
More than 15 players, or lots exploring at once? Go up to Premium (8 GB). Not sure? Email hello@dsnservers.com.
Planned launch price in USD, billed monthly once ordering opens, with a 7-day refund window.
How to make a Tools for builders server on your own PC
What's specific to Tools for builders, step by step. The full walkthrough for any pack: how to make a modded Minecraft server.
- Install Java 21.
Check with
java -version. Java version chart. - Get the server files.
Build them from the .mrpack, as in server files above.
- Start it and accept the EULA.
Run the start script in the server files, or
java -jaron the Fabric 1.21.1 server launcher, then seteula=trueineula.txtif you accept Mojang's EULA (EULA step). - Set the RAM with
-Xmx, sized from the table above. - Let friends connect: forward TCP 25565, or use a tunnel or host behind CGNAT (can't connect?).
Or run Tools for builders on DSN
Once we relaunch (join the launch list), on DSN you'd install Tools for builders from the panel's Modrinth modpack installer (version 1.0.4), pick Java 21 on the Startup tab and accept the EULA in the console. No port forwarding.
How to play Tools for builders with friends
Each player installs Tools for builders version 1.0.4 with the Modrinth App or Prism Launcher, the same version as the server, and adds the server's address under Multiplayer.
Different versions of Tools for builders on the server and a client show up as Mismatched mod channel list or mod rejections. Why friends can't join, timeouts included.
Lag and performance on Tools for builders
Can't keep up! Is the server overloaded? means ticks take longer than 50 ms; more RAM won't fix that once Tools for builders has enough (tick lag guide). For Tools for builders:
- Measure first: spark's
/spark tpsand profiler work on 1.21.1 and name the mod or machine using the tick time. - Distances:
view-distance=8and a lowersimulation-distanceinserver.properties. - Pre-generate: Chunky for 1.21.1,
/chunky radius 3000then/chunky start, before people explore.
Common Tools for builders crashes
What a Fabric 1.21.1 server running Tools for builders hits most. For any other error, paste the log into the free crash log analyzer.
- Wrong Java version. Tools for builders on Minecraft 1.21.1 needs Java 21. Started on Java 17, it stops with
UnsupportedClassVersionError: ... class file version 65.0, this version of the Java Runtime only recognizes class file versions up to 61.0. Java version fix. - Out of memory. Tools for builders (14 mods on the server) needs about 2 GB for 1–3 players;
java.lang.OutOfMemoryErrormeans it ran out. Out-of-memory fix. - Client-only mod on the server. Tools for builders includes 27 client-only mods, which a server install skips; copying a player's mods folder brings them back and stops the server. Check a mods list with the client-or-server-side checker. Client-only mod fix.
- After adding or updating a mod. Mods you add to Tools for builders by hand usually crash it with a missing dependency or a mixin conflict.
- Ticking entity or block entity. The crash report names it and gives its coordinates. Ticking entity fix.
Updates and support
Before moving Tools for builders past version 1.0.4, back up the world: see updating a modpack server without losing your world.
Bugs in Tools for builders itself go to its authors through its Modrinth page. Server problems on DSN: hello@dsnservers.com or Discord.
Packs like Tools for builders
More: all modpack guides and how to make a modded server.
Run Tools for builders on DSN when we relaunch.
Our pick, Standard: 4 GB, planned at $16/month.
DSN Servers isn't affiliated with Tools for builders or Modrinth. The pack's name, icon, summary and stats come from Modrinth's public API (checked October 4, 2026).