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CustomLagMinecraft mod for 1.21.11

Fabric mod to simulate lag for servers and single player worlds by delaying packets from sending and receiving

server onlynewest supported release 1.21.11UtilityGame MechanicsManagement
Latest version
1.1.1+1.21.6-1.21.8
Minecraft
1.21 to 1.21.11
Java
Java 21+
Loader
Fabric
Licence
MIT
Downloads
1.5k
Updated
10 mo ago
Available on
Modrinth
Space NodeOur hosting

Host CustomLag servers

One click and CustomLag is installed with the right loader, on hardware built for it.

  • 1.21.11
  • Fabric
  • One click mod install
  • Loader matched for you
  • Ryzen CPUs
  • NVMe SSD
Deploy a serverFrom €0.90 per GB

Screenshots

Click a screenshot to open it. Screenshots are served from the author’s own host and belong to them.

Minecraft versions

Every version CustomLag declares support for, newest first, with the Java runtime that version needs.

Other mods
MinecraftThroughJavaEvidenceReleased
1.21.11Fabric21+declared9 Dec 2025
1.21.10Fabric21+declared7 Oct 2025
1.21.9Fabric21+declared30 Sept 2025
1.21.8Fabric21+declared17 Jul 2025
1.21.7Fabric21+declared30 Jun 2025
1.21.6Fabric21+declared17 Jun 2025
1.21.5Fabric21+declared25 Mar 2025
1.21.4Fabric21+declared3 Dec 2024
1.21.3Fabric21+declared23 Oct 2024
1.21.2Fabric21+declared22 Oct 2024
1.21.1Fabric21+declared8 Aug 2024
1.21Fabric21+declared13 Jun 2024

Download

From CustomLag’s own host. Nothing is re-hosted here.

For Minecraft 1.21.11

Choose the loader you use before downloading.

  • Fabric

    1.1.0+1.21.11 · 29 Dec 2025 · customlag-1.1.0+1.21.11.jar

    Get Fabric

Most recently published release

1.1.1+1.21.6-1.21.8release29 Dec 2025

customlag-1.1.1+1.21.6-1.21.8.jar · 0.8 MB · for 1.21.8, 1.21.7, 1.21.6 · Fabric

Download this release
4484e74df8e5…
Older versions6
  • 1.1.1+1.21.529 Dec 20251.21.50.8 MB29 downloadse03f3e0c4a5f…Get
  • 1.1.0+1.21.1129 Dec 20251.21.110.8 MB775 downloads72a607d0c302…Get
  • 1.1.0+1.21.9-1.21.1029 Dec 20251.21.10, 1.21.90.8 MB111 downloads4f2552ad315d…Get
  • 1.1.0+1.21.5-1.21.829 Dec 20251.21.8, 1.21.7, 1.21.6, 1.21.50.8 MB22 downloads41f199e18005…Get
  • 1.1.0+1.21-1.21.429 Dec 20251.21.4, 1.21.3, 1.21.2, 1.21.1, 1.210.8 MB354 downloads919d212ae693…Get
  • 1.015 Aug 20251.21.413.7 MB134 downloads5041f8b9bcf0…Get

Frequently asked

Does CustomLag work on Minecraft 1.21.11?

Yes. 1.21.11 is the newest Minecraft version CustomLag declares support for, and the claim comes from the author's own release metadata rather than from a compatibility list somebody maintains by hand.

Which Minecraft versions does CustomLag support?

Everything the author has declared, from 1.21 up to 1.21.11. The full list is in the table above, with the Java runtime each version needs next to it.

Do I need to install CustomLag on the client or the server?

The server only. Players join with an ordinary Minecraft client and install nothing.

Which platform or loader does CustomLag support?

Fabric. A build for one platform or loader will not necessarily load on another, so this is the first thing to check before the Minecraft version.

Which Java version do I need for CustomLag?

Among the supported Minecraft releases above, the highest recorded requirement is Java 21 or newer. Use the requirement for the exact Minecraft version you run; previews and snapshots may differ.

What licence is CustomLag under?

MIT, as stated by the author on the platform we synced it from. Check the project's own page before redistributing or bundling it.

How do I install CustomLag?

Install the matching loader first, then put the downloaded file in your mods folder and start the game. The loader, the mod and Minecraft all have to be on the same version, which is the usual reason a mod does not appear in game.

Where do I download CustomLag safely?

Start with the author's page on Modrinth, which is where the data here is synced from. MCReference does not host or repackage files. When available, recorded download links go to the source for that release; verify the publisher, filename and any available checksum before running it.

Works on the same versions

Ordered by how much of the recent Minecraft version coverage overlaps, not by popularity.

Cloth Config API (Fabric/Forge/NeoForge)Config Screen API for MinecraftJourneyMapReal-time map used for mapping in-game or your browser as you explore.Architectury APIAn intermediary api aimed to ease developing multiplatform mods.Jade 🔍Shows information about what you are looking at. (Hwyla/WAILA fork for Minecraft 1.16+)Collective🎓 Collective is a shared library with common code for all of Serilum's mods.Xaero's MinimapDisplays the nearby world terrain, players, mobs, entities in the corner of your screen. Lets you create waypoints which help you find the locations you've marked.

Details from Modrinth, where the author last updated it on 29 Dec 2025. We do not host files or republish descriptions. Available download links point to the author’s own release.

Is this information wrong or missing something? .