rmcl

Rusty MineCraft Launcher. or Rust MineCraft cLi. pick whichever sounds better to you.

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about

we all love TUIs. and we all know the official Minecraft launcher is not exactly a joy to use (performance wise; no hatespeech here). so here's rmcl, a fully featured Minecraft launcher that lives in your terminal. written in Rust.

it does everything you'd expect from a launcher.

features

modpacks and accounts

Browse Modrinth and CurseForge modpacks or import Modrinth, CurseForge, and MultiMC/Prism archives (including GTNH packs in that format). Direct imports accept a local archive, Modrinth URL, or Modrinth project slug. CurseForge requires a build-time API key. Multiple Microsoft accounts and offline accounts are supported.

authentication

rmcl uses its own Microsoft client ID for Minecraft account authentication.

Authentication is performed through Microsoft’s official services.

CurseForge API

Git, source, and Cargo builds use rmcl's dedicated API key unless CURSEFORGE_API_KEY is set at compile time. An empty or whitespace-only override disables CurseForge. Use of the API is subject to the CurseForge 3rd Party API Terms and Conditions. Keys supplied for rmcl are for rmcl builds only. Forks, rebranded applications, and unrelated projects must use their own key. Keys included in source or compiled binaries are extractable; do not publish a private key.

installation

macOS / Linux

prebuilt archives are attached to each GitHub release.

# Homebrew
brew install objz/tap/rmcl

Linux archives and Homebrew installations require the system libxcb runtime package (libxcb1 on Debian/Ubuntu, libxcb on Arch).

An ARM64 launcher build still needs Minecraft natives for that platform. For example, Minecraft 1.20.1 supplies macOS ARM64 natives but no Linux ARM64 natives; using a custom GLFW library alone does not provide the other required libraries.

Windows

release builds include a .zip archive and an .msi. WinGet packages are submitted from release CI and become available after review.

# WinGet
winget install Objz.Rmcl

Arch Linux

# from source (release tarball)
paru -S rmcl

# prebuilt binary
paru -S rmcl-bin

# latest git
paru -S rmcl-git

Nix

nix run github:objz/rmcl
nix profile install github:objz/rmcl

the flake builds rmcl from source. To use your own key instead, override it at build time:

CURSEFORGE_API_KEY=your-key nix build --impure .#

Minecraft 1.12 and older currently fail to launch because rmcl doesn't pass -Djava.library.path for legacy version profiles.

Cargo

cargo install rmcl

from source

requires a Rust toolchain and a JDK (javac and jar on PATH). Linux builds also require the libxcb development package (libxcb1-dev on Debian/Ubuntu, libxcb on Arch).

git clone https://github.com/objz/rmcl.git
cd rmcl
cargo build --release

where things live

config & data

settings, accounts, instances, and cached game metadata.

These are default locations. On Linux, XDG_CONFIG_HOME, XDG_DATA_HOME, and XDG_CACHE_HOME override the corresponding base directories. Instance and metadata paths can also be changed in config.toml.

each instance has an instance.json for its config and a minecraft/ directory with the actual game files.

Launcher settings saved through the TUI apply immediately, except changes to instances_dir, meta_dir, and image_protocol, which require a restart. Settings files opened through rmcl's editor shortcut are reloaded after saves; otherwise, restart rmcl after editing config.toml externally. When neither global nor instance java_path is set, rmcl selects Java automatically. Global JVM arguments and environment variables are applied before per-instance values. Instances can explicitly inherit the launcher window mode and resolution defaults.

[general]
check_modpack_updates = true
check_content_updates = true

[defaults]
memory_min = "512M"
memory_max = "2G"
jvm_args = []
environment = {}
window_mode = "windowed"
resolution = [854, 480]

[ui]
image_protocol = "auto"
hidden_shortcut_hints = [] # all, main, instances, content, accounts, settings, popups

[content]
preferred_provider = "modrinth"
preferred_provider_only = false
ask_on_provider_conflict = true

Use hidden_shortcut_hints = ["main"] to keep only popup guides, ["all"] to hide every guide, or list individual areas to hide them selectively.

logs

launcher logs are per-session and contain rmcl's own output. instance launch logs capture game stdout/stderr per launch.

performance

the following measurements were taken from a release build on a Linux development system. they are intended as a practical reference, since terminal, window size, content count, and hardware all affect the result.

idle instance list

over a 60 second sample, the instance list used 497.81 ms of CPU time. that is about 0.83% of one CPU core. resident memory was 15.1 MiB.

idle mods list

with a populated mods list and its icons loaded, a 60 second sample used 664.77 ms of CPU time. that is about 1.11% of one CPU core. resident memory was 67.2 MiB, with a peak of 69.9 MiB.

scrolling mods list

continuously scrolling through the populated mods list used 1000.02 ms of CPU time over 30 seconds. that is about 3.33% of one CPU core.

In comparison, the Modrinth AppImage used approximately 14-30% of a CPU core and about 327 Mib of memory while browsing the mod list.

themes

rmcl ships with 10 built-in themes:

catppuccin · dracula · nord · gruvbox · one-dark · solarized · tailwind · tokyo-night · rose-pine · terminal

pick one in ~/.config/rmcl/theme.toml:

theme = "gruvbox"
border_style = "rounded"   # rounded | plain | double | thick

custom themes

drop a TOML file in ~/.config/rmcl/theme/ and reference it by name, or point theme at an absolute path. keys are flat and top level, don't nest them under [theme]. only name, id and accent are required, the rest falls back to a default:

# ~/.config/rmcl/theme/my-theme.toml
name = "My Theme"
id = "my-theme"

accent = { Rgb = [249, 115, 22] }
accent_dim = "#7f5539"
text = "#cdd6f4"
text_dim = "DarkGray"
text_bright = "#ffffff"
success = "#a6e3a1"
error = "#f38ba8"
warning = "#f9e2af"
info = "#89dceb"
diff_added = "#a6e3a1"
diff_removed = "#f38ba8"
diff_context = "DarkGray"
border = "#585b70"
surface = "#313244"
background = "#1e1e2e"

then set theme = "my-theme" in theme.toml.

colors accept "#f97316", ANSI names ("Red", "LightBlue"), { Rgb = [r, g, b] } or { Indexed = n }.

note that [custom] in theme.toml overrides colors of the selected theme, whether built-in or loaded from a file; it doesn't define a standalone theme. border_style belongs at the top level of theme.toml, not in a custom theme file.

contributing

contributions are welcome. fork it, branch it, PR it. see CONTRIBUTING.md

license

Copyright (C) 2026 Constantin Bauer

This project is licensed under the GNU General Public License v3.0. see LICENSE.