UltimMC

Free plan LinuxMacWindows

What UltimMC is

UltimMC is a free, open-source custom Minecraft launcher for managing separate game instances and using offline accounts while staying close to the original launcher. It is a fork of MultiMC and runs on Linux, macOS, and Windows. Windows downloads cover 32-bit and 64-bit systems. Linux users can use a 64-bit download, Debian or Ubuntu .deb packages, or an AUR package. The macOS build supports version 10.14 and newer. Setup allows a local account with a chosen username or an Ely.by account using email and password. The project says an MSA API key for Microsoft authentication is included and asks forks to replace or remove it. Builds come directly from GitHub Actions. Updating currently means replacing designated files and folders with newer downloads; a better updater is in development. The software has no warranty. Problems specific to UltimMC can be reported through its repository issue tracker.

Who it suits

UltimMC suits Minecraft players who want separate instances, offline-account options, and a launcher for Linux, macOS, or Windows. It also fits users comfortable with manual updates and repository-based support.

What it does well

Free and open source
Manages multiple separate instances
Supports offline accounts
Runs on Linux, macOS, and Windows
Offers several Linux package formats

What to know first

Automatic updates are unavailable
Updates require replacing files and folders
Provided without warranty
macOS requires version 10.14 or newer

Plans

Plan	Billed and limits	Price
UltimMC	No paid plans or usage limits stated	Free

As github.com lists them, read 12 Oct 2026. The maker's own page has the final word.

Verdict

UltimMC provides a no-cost launcher with broad desktop support and separate-instance management. Manual updating and repository issue support are important parts of its current use.

Facts from UltimMC's own pages

Account options: The setup instructions describe adding a local account with a chosen username or adding an Ely.by account using an email and password. · github.com, 12 Oct 2026
Automatic updates: No · github.com, 22 Sept 2026
Build source: The project says its available builds are taken directly from its GitHub Actions. · github.com, 12 Oct 2026
Linux support: A 64-bit Linux download is available, along with a .deb package for Debian and Ubuntu and an AUR package. · github.com, 12 Oct 2026
macOS support: A macOS download is available for macOS 10.14 and newer. · github.com, 12 Oct 2026
Microsoft authentication: The project says it includes an MSA API key for Microsoft authentication and asks forks to remove the key or set their own. · github.com, 12 Oct 2026
Organization: The UltimMC GitHub organization describes itself as dedicated to developing UltimMC and related software. · github.com, 12 Oct 2026
Project origin: The project is a fork of MultiMC. · github.com, 12 Oct 2026
Purpose: UltimMC is a custom Minecraft launcher for managing multiple instances and using offline accounts while keeping as close as possible to the original. · github.com, 12 Oct 2026
Separate instances: Yes · github.com, 22 Sept 2026
Support: Users can create a repository issue for problems specific to UltimMC; the README says not to contact the main MultiMC developers about problems with this launcher. · github.com, 12 Oct 2026
Update process: Updating currently involves replacing replaceable files and folders with newer downloads; the project says a better update system is in the works. · github.com, 12 Oct 2026
Warranty: The software is provided without any warranty. · github.com, 12 Oct 2026
Windows support: Direct downloads are available for 32-bit and 64-bit Windows. · github.com, 12 Oct 2026

Where UltimMC stands on Freedom251

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