ModsFinder

relauncher

by juanmuscaria

Relauncher lets a library mod restart the Java process with extra JVM arguments before Minecraft finishes loading, so relaunch-dependent mods can be installed by dropping a single JAR.

FabricForgeNeoForgeQuiltClient or server, optionalMozilla Public License 2.0Open source1.6.4 – 26.1.2

What it does

Relauncher is a library for Java applications that need JVM flags, garbage collection tuning or system properties in place before the game starts. It restarts the JVM process early in startup, before significant game state is initialized, and passes the added arguments through transparently. Launchers that start the game still see one unbroken process, with no extra windows or leftover processes.

Relauncher is aimed at modpack tooling and at other mods that need to trigger a relaunch after installing dependencies or configuring themselves. Other mods can inject arguments by registering a CommandLineProvider through ServiceLoader, without calling the API directly and without depending on the library at runtime beyond a compile-only dependency. The config file's enabled flag only controls the arguments listed in that file. The mod works on Linux, Windows and macOS across both x86-64 and aarch64 processors, and is published for Fabric, Forge, NeoForge and Quilt. Its latest file is 1.1.0 for 26.1.2.

Key features

  1. Custom JVM arguments

    Arguments such as -XX:+AlwaysPreTouch and extra system properties can be added through the config file.

  2. Three relaunch strategies

    Relauncher tries three ways of restarting the JVM, in a set order of preference, and uses the first that works.

  3. Argument injection by other mods

    Mods that register a CommandLineProvider service are scanned from the mods folder and can add arguments on their own.

  4. Debug logging

    Setting relauncher.debug to true logs the full command line, argument assembly and strategy selection, which helps find why a relaunch fails.

Compatibility

Latest build for each game version and loader.

26.x3 of 3 versions with builds
26.1.21.1.01.1.01.1.01.1.0
26.1.11.1.01.1.01.1.01.1.0
26.11.1.01.1.01.1.01.1.0
1.21.x12 of 12 versions with builds
1.21.111.1.01.1.01.1.01.1.0
1.21.101.1.01.1.01.1.01.1.0
1.21.91.1.01.1.01.1.01.1.0
1.21.81.1.01.1.01.1.01.1.0
1.21.71.1.01.1.01.1.01.1.0
1.21.61.1.01.1.01.1.01.1.0
1.21.51.1.01.1.01.1.01.1.0
1.21.41.1.01.1.01.1.01.1.0
1.21.31.1.01.1.01.1.01.1.0
1.21.21.1.01.1.01.1.01.1.0
1.21.11.1.01.1.01.1.01.1.0
1.211.1.01.1.01.1.01.1.0
1.20.x7 of 7 versions with builds
1.19.x5 of 5 versions with builds
1.18.x3 of 3 versions with builds
1.17.x2 of 2 versions with builds
1.16.x6 of 6 versions with builds
1.15.x3 of 3 versions with builds
1.14.x5 of 5 versions with builds
1.13.x2 of 2 versions with builds
ReleaseBetaAlphaNot available

Only full game releases are shown. This mod publishes no snapshot builds.

35 older game versions (1.6.4 – 1.13) not shown. All files on Modrinth

How it compares

Full comparison

Crash Assistant is a client-side only mod released under a custom license that is not open source, with files for 1.6.4 – 26.3 on Fabric, Forge, NeoForge, Quilt and Legacy Fabric. Crash Command is open source under the MIT License, works on either side and needs neither, and has files for 1.19 – 1.21.8 on Fabric only. Server Restart Command is server-side only, open source under the MIT License, and published for 26.1 – 26.2 on Fabric.

ModLoadersGame versionsEnvironmentUpdated
relauncherFabric, Forge, NeoForge and Quilt1.6.4 – 26.1.2Client or server, optional2026-04-26
Crash AssistantFabric, Forge, NeoForge, Quilt and Legacy Fabric1.6.4 – 26.3Client-side only2026-09-20
Crash CommandFabric1.19 – 1.21.8Client or server, optional2025-06-28
Server Restart CommandFabric26.1 – 26.2Server-side only2026-07-08

Questions

Does Relauncher need to be installed on both sides?

No. Either side can run it, and neither needs it. It acts on the launcher's JVM arguments when the game starts.

Why isn't the relaunch working the way it should?

Set relauncher.debug to true in the launcher's JVM arguments. The log then shows the full command line, argument assembly and the strategy selected for the restart.

How do other mods use Relauncher without calling its API?

They implement CommandLineProvider and list it in a services file named after that interface under META-INF, and Relauncher finds the file when it scans the mods folder.

In the catalog

relauncher is one of 3,514 Library mods on ModsFinder, and one of 2,348 Library mods for Fabric. 15,189 mods support Minecraft 26.1.2.

Library mods3,514Fabric modsMods for 26.1.215,189

More from juanmuscaria

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Similar mods

Fabric API1.14 – 26.3Cloth Config API1.14 – 26.3YetAnotherConfigLib (YACL)1.19 – 26.3Architectury API1.16.5 – 26.3Just Enough Items (JEI)1.8 – 26.3Geckolib1.12.2 – 26.3

What the author says

JVM relaunch library for Java based applications. Drop a single JAR into your mods folder, and it should work from Minecraft 1.6.4 to the latest version, or on Hytale Server as an early plugin or regular plugin. The relaunch happens very early during startup, before any significant game state is initialized. External…
juanmuscaria, on the Modrinth page

Official listing

Owner
juanmuscaria
Published
2026-03-21
Updated on Modrinth
2026-04-26
Facts verified
2026-10-15

Tags

LibraryManagementUtilityCursed
Open on ModrinthCompare