mod
CustomLagMinecraft mod for 1.21.11
Fabric mod to simulate lag for servers and single player worlds by delaying packets from sending and receiving
- 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
- 7 mo ago
- Available on
- Modrinth
PartnerHost 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
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.
| Minecraft | Through | Java | Evidence | Released |
|---|---|---|---|---|
| 1.21.11 | Fabric | 21+ | declared | 9 Dec 2025 |
| 1.21.10 | Fabric | 21+ | declared | 7 Oct 2025 |
| 1.21.9 | Fabric | 21+ | declared | 30 Sept 2025 |
| 1.21.8 | Fabric | 21+ | declared | 17 Jul 2025 |
| 1.21.7 | Fabric | 21+ | declared | 30 Jun 2025 |
| 1.21.6 | Fabric | 21+ | declared | 17 Jun 2025 |
| 1.21.5 | Fabric | 21+ | declared | 25 Mar 2025 |
| 1.21.4 | Fabric | 21+ | declared | 3 Dec 2024 |
| 1.21.3 | Fabric | 21+ | declared | 23 Oct 2024 |
| 1.21.2 | Fabric | 21+ | declared | 22 Oct 2024 |
| 1.21.1 | Fabric | 21+ | declared | 8 Aug 2024 |
| 1.21 | Fabric | 21+ | declared | 13 Jun 2024 |
Download
From CustomLag’s own host. Nothing is re-hosted here.
customlag-1.1.1+1.21.6-1.21.8.jar · 0.8 MB · for 1.21.6, 1.21.7, 1.21.8
4484e74df8e5…Older versions6Hide older versions
- 1.1.1+1.21.529 Dec 20251.21.50.8 MB29 downloads
e03f3e0c4a5f…Get - 1.1.0+1.21.1129 Dec 20251.21.110.8 MB775 downloads
72a607d0c302…Get - 1.1.0+1.21.9-1.21.1029 Dec 20251.21.9, 1.21.100.8 MB111 downloads
4f2552ad315d…Get - 1.1.0+1.21.5-1.21.829 Dec 20251.21.5, 1.21.6, 1.21.7, 1.21.80.8 MB22 downloads
41f199e18005…Get - 1.1.0+1.21-1.21.429 Dec 20251.21, 1.21.1, 1.21.2, 1.21.3, 1.21.40.8 MB354 downloads
919d212ae693…Get - 1.015 Aug 20251.21.413.7 MB134 downloads
5041f8b9bcf0…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 loader does CustomLag need?
Fabric. A build for one loader will not load on another, so this is the first thing to check before the Minecraft version.
Which Java version do I need for CustomLag?
Java 21 or newer, because that is what the newest Minecraft release it supports requires. The requirement comes from the game rather than from the mod itself.
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?
From the author's own page on Modrinth, which is where the data here is synced from. MCReference never mirrors, re-hosts or repackages a file: every download button points at the original source, so you get exactly what the author published.
Works on the same versions
Ordered by how much of the recent Minecraft version coverage overlaps, not by popularity.
Is this information wrong or missing something? .