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Onyx Launcher
What it is
Onyx Launcher is a free, open-source desktop Minecraft launcher for Windows and Linux. It manages separate instances and supports Vanilla, Fabric, NeoForge, Forge, and Quilt, with modpack imports and a built-in Modrinth catalog for browsing, installing, and updating mods and modpacks. Onyx automatically detects, downloads, and isolates Eclipse Temurin Java 8, 17, or 21, and it supports automatic updates. Its bundled Java agent measures in-game FPS, average frame times, and stutters. Diagnostic tools analyze logs, track memory and garbage-collection pauses, and use Crash Bisect to search controlled launches for conflicting mods. World Guard creates safety snapshots before risky operations and supports rollbacks. Ghost Mode unloads launcher components from system memory when Minecraft starts. Microsoft sign-in uses OAuth Device Flow, while offline mode with custom skins is available. Windows builds are currently unsigned. The plan is free.
For and against
For
- Supports five Minecraft loaders plus Vanilla
- Built-in Modrinth mod and modpack catalog
- Manages Eclipse Temurin Java versions
- Crash Bisect searches for conflicting mods
- World Guard supports safety snapshots and rollbacks
Against
- Windows builds are currently unsigned
- SmartScreen may show a warning
- Separate instances require desktop Windows or Linux
- It is unaffiliated with Microsoft, Mojang Studios, and Modrinth
The verdict
Onyx combines instance management, modpack access, Java setup, and Minecraft diagnostics in one launcher. Unsigned Windows builds and its independent affiliation statement are key considerations.
Who it suits
Onyx suits Minecraft players on Windows or Linux who want separate instances, mod-loader support, Modrinth access, Java management, and diagnostic tools. It also fits users who want offline mode or rollback snapshots.
Plans and prices
Free and open source
100% Free & Open Source · MIT licensed
Read 8 Oct 2026 · lonestill.github.io
On the record
- 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.lonestill.github.io · read 8 Oct 2026
- Automatic updates
- Yesgithub.com · read 19 Sep 2026
- Built-in modpack catalog
- Yesgithub.com · read 19 Sep 2026
- Crash diagnostics
- Onyx analyzes logs and tracks memory and garbage-collection pauses, and Crash Bisect searches controlled launches for conflicting mods.lonestill.github.io · read 8 Oct 2026
- Download integrity
- GitHub releases publish SHA-256 checksums alongside binaries, and the maker says builds are compiled through public GitHub Actions CI.lonestill.github.io · read 8 Oct 2026
- Ghost Mode
- When Minecraft launches, Ghost Mode unloads the launcher window, WebContents, and GPU processes from system memory.lonestill.github.io · read 8 Oct 2026
- Java runtime
- Onyx automatically detects, downloads, and isolates Eclipse Temurin Java 8, 17, or 21 as needed.lonestill.github.io · read 8 Oct 2026
- Java runtime management
- Yesgithub.com · read 19 Sep 2026
- License and affiliation
- Onyx is MIT licensed and says it is independent and unaffiliated with Microsoft, Mojang Studios, or Modrinth.lonestill.github.io · read 8 Oct 2026
- Loaders
- The launcher supports Fabric, NeoForge, Forge, Quilt, and Vanilla.lonestill.github.io · read 8 Oct 2026
- Mod catalog
- Users can browse, install, and update Modrinth mods and modpacks from the launcher.lonestill.github.io · read 8 Oct 2026
- Mod loader support
- multiplegithub.com · read 19 Sep 2026
- Modpack import
- bothgithub.com · read 19 Sep 2026
- Performance telemetry
- Onyx Probe measures in-game FPS, average frame times, and stutters through a bundled Java agent.lonestill.github.io · read 8 Oct 2026
- Separate instances
- Yesgithub.com · read 19 Sep 2026
- Support
- The launcher offers redacted support bundles for troubleshooting.lonestill.github.io · read 8 Oct 2026
- Supported platforms
- The download page lists Windows 10/11 x64 and modern Linux x64, with AppImage, .deb, .rpm, and portable archive options for Linux.lonestill.github.io · read 8 Oct 2026
- Unsigned builds
- Windows builds are currently unsigned, so SmartScreen may show a warning; the site advises checking the published SHA-256 checksum.lonestill.github.io · read 8 Oct 2026
