Freedom251 › Minecraft Launchers
Onyx Launcher
What Onyx Launcher is
Onyx Launcher is a free, open-source desktop launcher for Minecraft on Windows and Linux. It manages separate game instances and supports Vanilla, Fabric, NeoForge, Forge, and Quilt. Its built-in catalog lets players browse, install, and update Modrinth mods and modpacks, and it supports modpack imports. Onyx can detect, download, and isolate Eclipse Temurin Java 8, 17, or 21 as needed, and it updates automatically.
The launcher includes tools for monitoring performance and investigating problems. Onyx Probe measures in-game FPS, average frame times, and stutters. The launcher also analyzes logs and tracks memory use and garbage-collection pauses; Crash Bisect runs controlled launches to search for conflicting mods. World Guard saves safety snapshots before dangerous operations and supports rollbacks. When Minecraft launches, Ghost Mode unloads the launcher window, WebContents, and GPU processes from system memory.
Microsoft sign-in uses OAuth Device Flow, and Onyx says it does not handle the user's password. Offline mode with custom skins is also available. The project is MIT licensed and describes itself as independent and unaffiliated with Microsoft, Mojang Studios, or Modrinth.
Who it suits
Onyx suits Minecraft players on Windows or Linux who want separate instances, multiple loader options, and Modrinth modpack tools in one launcher. Its Java management, diagnostics, and world snapshots may also suit players who want help managing runtimes and troubleshooting mod conflicts.
What it does well
- Supports separate Minecraft instances and five loader options.
- Browse, install, and update Modrinth mods and modpacks in the launcher.
- Automatically manages Eclipse Temurin Java 8, 17, or 21.
- Includes performance measurements, log analysis, and Crash Bisect.
- World Guard creates snapshots and supports safe rollbacks.
- Free, open source, and MIT licensed.
What to know first
- Windows builds are unsigned, so SmartScreen may show a warning.
- Downloads are for Windows 10/11 x64 or modern Linux x64.
Plans
| Plan | Billed and limits | Price |
|---|---|---|
| Free and open source | 100% Free & Open Source · MIT licensed | Free |
As github.com lists them, read 8 Oct 2026. The maker's own page has the final word.
Getting started
- Open the Onyx Launcher website on GitHub.
- Choose the download for Windows 10/11 x64 or modern Linux x64.
- For Linux, choose an AppImage, .deb, .rpm, or portable archive.
- Check the published SHA-256 checksum for the downloaded binary.
- Sign in with Microsoft using OAuth Device Flow, or use offline mode with custom skins.
Verdict
Choose Onyx if you want a free launcher with instance management, Modrinth catalog access, Java runtime handling, and built-in diagnostics. Windows users should account for the unsigned builds, which may prompt a SmartScreen warning.
Questions
Is Onyx Launcher free?
Yes. Its plan is listed as free, and the launcher is described as free and open source.
Which platforms does Onyx support?
The download page lists Windows 10/11 x64 and modern Linux x64. Linux downloads are offered as AppImage, .deb, .rpm, and portable archive options.
Which Minecraft loaders and mod catalogs does it support?
It supports Fabric, NeoForge, Forge, Quilt, and Vanilla. Its built-in catalog supports browsing, installing, and updating Modrinth mods and modpacks.
Is Onyx Launcher open source?
Yes. It is MIT licensed.
How does account sign-in work?
Microsoft sign-in uses OAuth Device Flow. Onyx says it never handles the user's password; offline mode with custom skins is also available.
Can Windows show a security warning?
Windows builds are currently unsigned, so SmartScreen may show a warning. The site advises checking the published SHA-256 checksum.
Facts from Onyx Launcher's own pages
- 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, 8 Oct 2026
- Automatic updates
- Yes · github.com, 19 Sept 2026
- Built-in modpack catalog
- Yes · github.com, 19 Sept 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, 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, 8 Oct 2026
- Free plan
- Yes · github.com, 19 Sept 2026
- Ghost Mode
- When Minecraft launches, Ghost Mode unloads the launcher window, WebContents, and GPU processes from system memory. · lonestill.github.io, 8 Oct 2026
- Java runtime
- Onyx automatically detects, downloads, and isolates Eclipse Temurin Java 8, 17, or 21 as needed. · lonestill.github.io, 8 Oct 2026
- Java runtime management
- Yes · github.com, 19 Sept 2026
- License and affiliation
- Onyx is MIT licensed and says it is independent and unaffiliated with Microsoft, Mojang Studios, or Modrinth. · lonestill.github.io, 8 Oct 2026
- Loaders
- The launcher supports Fabric, NeoForge, Forge, Quilt, and Vanilla. · lonestill.github.io, 8 Oct 2026
- Mod catalog
- Users can browse, install, and update Modrinth mods and modpacks from the launcher. · lonestill.github.io, 8 Oct 2026
- Mod loader support
- multiple · github.com, 19 Sept 2026
- Modpack import
- both · github.com, 19 Sept 2026
- Performance telemetry
- Onyx Probe measures in-game FPS, average frame times, and stutters through a bundled Java agent. · lonestill.github.io, 8 Oct 2026
- Separate instances
- Yes · github.com, 19 Sept 2026
- Support
- The launcher offers redacted support bundles for troubleshooting. · lonestill.github.io, 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, 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, 8 Oct 2026
- What it does
- Onyx is an open-source desktop Minecraft launcher built with React and Electron. · lonestill.github.io, 8 Oct 2026
- World safety
- World Guard makes safety snapshots before dangerous operations and supports safe rollbacks. · lonestill.github.io, 8 Oct 2026
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