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SPECIFICTION
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Onyx Launcher

github.com

Free plan WindowsLinux
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Spec score 8.4 #18 of 75 in Minecraft Launchers

What it is

Onyx Launcher is a free, open-source desktop Minecraft launcher for Windows and Linux. It manages separate instances, imports modpacks and supports Fabric, NeoForge, Forge, Quilt and Vanilla. A built-in Modrinth catalog lets users browse, install and update mods and modpacks, while automatic updates and Java runtime management are included. Onyx can detect, download and isolate Eclipse Temurin Java 8, 17 or 21 as needed. Diagnostic features measure in-game FPS, average frame times and stutters, analyze logs, track memory and garbage-collection pauses, and use Crash Bisect to look for conflicting mods through controlled launches. World Guard creates safety snapshots before risky operations and supports rollbacks. Ghost Mode unloads the launcher window, WebContents and GPU processes from memory when Minecraft starts. Microsoft sign-in uses OAuth Device Flow, and offline mode with custom skins is available. Windows builds are currently unsigned; published SHA-256 checksums can be checked. The MIT-licensed project says it is independent of Microsoft, Mojang Studios and Modrinth.

Spec sheet

What it does
Onyx is an open-source desktop Minecraft launcher built with React and Electron.Read 8 Oct 2026 · lonestill.github.io
Free plan
YesRead 19 Sep 2026 · github.com
Support
The launcher offers redacted support bundles for troubleshooting.Read 8 Oct 2026 · lonestill.github.io
Account sign-in
Microsoft sign-in uses OAuth Device Flow, and Onyx says it never handles the user's password; offline mode with custom skins is also available.Read 8 Oct 2026 · lonestill.github.io
Automatic updates
YesRead 19 Sep 2026 · github.com
Built-in modpack catalog
YesRead 19 Sep 2026 · github.com
Crash diagnostics
Onyx analyzes logs and tracks memory and garbage-collection pauses, and Crash Bisect searches controlled launches for conflicting mods.Read 8 Oct 2026 · lonestill.github.io
Download integrity
GitHub releases publish SHA-256 checksums alongside binaries, and the maker says builds are compiled through public GitHub Actions CI.Read 8 Oct 2026 · lonestill.github.io
Ghost Mode
When Minecraft launches, Ghost Mode unloads the launcher window, WebContents, and GPU processes from system memory.Read 8 Oct 2026 · lonestill.github.io
Java runtime
Onyx automatically detects, downloads, and isolates Eclipse Temurin Java 8, 17, or 21 as needed.Read 8 Oct 2026 · lonestill.github.io
Java runtime management
YesRead 19 Sep 2026 · github.com
License and affiliation
Onyx is MIT licensed and says it is independent and unaffiliated with Microsoft, Mojang Studios, or Modrinth.Read 8 Oct 2026 · lonestill.github.io
Loaders
The launcher supports Fabric, NeoForge, Forge, Quilt, and Vanilla.Read 8 Oct 2026 · lonestill.github.io
Mod catalog
Users can browse, install, and update Modrinth mods and modpacks from the launcher.Read 8 Oct 2026 · lonestill.github.io
Mod loader support
multipleRead 19 Sep 2026 · github.com
Modpack import
bothRead 19 Sep 2026 · github.com
Performance telemetry
Onyx Probe measures in-game FPS, average frame times, and stutters through a bundled Java agent.Read 8 Oct 2026 · lonestill.github.io
Separate instances
YesRead 19 Sep 2026 · github.com
Supported platforms
The download page lists Windows 10/11 x64 and modern Linux x64, with AppImage, .deb, .rpm, and portable archive options for Linux.Read 8 Oct 2026 · lonestill.github.io
Unsigned builds
Windows builds are currently unsigned, so SmartScreen may show a warning; the site advises checking the published SHA-256 checksum.Read 8 Oct 2026 · lonestill.github.io
World safety
World Guard makes safety snapshots before dangerous operations and supports safe rollbacks.Read 8 Oct 2026 · lonestill.github.io

Plans and prices

Free and open source Free 100% Free & Open Source · MIT licensed Read 8 Oct 2026 · lonestill.github.io

Every Onyx Launcher plan and price →

Strong points and limits

Strong points

  • Free and MIT licensed
  • Supports five mod-loader choices
  • Built-in Modrinth catalog
  • Automatic Java runtime management
  • Crash and world-safety tools

Limits

  • Windows builds are currently unsigned
  • No free trial is offered

Who it suits

It suits Minecraft players on Windows or Linux who want instance management, mod catalog access and built-in diagnostics. It also fits users who prefer free, open-source software.

Verdict

Onyx Launcher combines broad Minecraft instance and mod support with Java handling, diagnostics and rollback tools. Users on Windows should account for the current SmartScreen warning risk from unsigned builds.

Where Specifiction places it

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