Prism Launcher: a legal, open-source Minecraft launcher

What Prism Launcher is

Prism Launcher is a free launcher for Minecraft Java Edition, distributed under the GPL-3.0 license. The project started in 2022 as a fork of MultiMC, an older community launcher whose development had slowed down. The Prism team took over, sped up releases and added integration with modern mod platforms (Modrinth, CurseForge).

The key feature of Prism is isolated instances. Each instance is a separate version of Minecraft with its own mods, resource packs, worlds and Java settings. You can keep a vanilla 1.21 instance, a 1.20.1 instance with Forge + 200 mods and a 1.7.10 instance for an old modpack side by side, and none of them affects the others. The official Mojang launcher does not offer that kind of isolation.

Prism is fully legal. It requires you to sign in with a real Microsoft/Mojang account that owns the game, so it does not bypass payment or verification. If you do not own the game, buy it at minecraft.net.

Prism vs the official Mojang launcher: advantages

The official Mojang launcher handles the basics well, but once you start modding the game its limits show quickly. Prism was designed specifically for working with mods and modpacks.

Prism does not replace the official launcher: you can have both on one account. Many players use the official one for quick vanilla games and Prism for modpacks and experiments.

How to install Prism Launcher (Windows, Mac, Linux)

Prism is available for all major systems. Download it only from the official site prismlauncher.org/download: fake copies from other domains can contain malware.

Windows

On the download page choose the Windows section. You have two options: the MSI installer (a traditional setup with Start menu integration) or a portable ZIP (unpack it anywhere, it runs without installation). On new ARM processors (Snapdragon X) get the ARM64 version: the x64 version works, but slower.

After installing, start Prism Launcher. On the first launch a wizard asks about the language, the location of the instances folder and the Java version.

macOS

For a Mac with an Apple Silicon processor (M1/M2/M3/M4) get the ARM64 package. For older Intel Macs, get the x64 version. The file is a DMG: open it and drag the Prism Launcher icon into the Applications folder. On the first launch macOS may report that the app comes from an "unidentified developer": right-click the icon and choose Open to get past the warning.

Linux

Linux has the most installation options:

• Flatpak (recommended, works everywhere): flatpak install flathub org.prismlauncher.PrismLauncher
• Arch / Manjaro: pacman -S prismlauncher
• Fedora: a package in COPR g3tchoo/prismlauncher
• Ubuntu / Debian: the AppImage from the official site or a package from a community PPA

On the Steam Deck, Prism installs from Discover (Flatpak) and works in both Gaming mode and Desktop mode. More about mods after you install Prism: how to install mods for Minecraft.

Setting up your Microsoft / Mojang account

To play, Prism needs you to be signed in with a Microsoft account (old Mojang accounts were migrated to Microsoft in 2022). If you do not own the game, buy it at minecraft.net: Prism does not work without a legitimate account that owns Minecraft.

Adding an account

After starting Prism, click the account icon in the top right corner or choose Accounts → Manage Accounts. Click Add Microsoft. The launcher opens your browser with the official Microsoft sign-in page: sign in with the same account that owns Minecraft.

After a successful sign-in, Prism shows your username and skin. You can add several accounts (for family, testing, alternative skins) and switch between them.

Offline mode

Prism offers an offline mode, useful when you play on a LAN without internet. Offline mode is unlocked only after you have signed in with a real account first, which confirms that you own a legitimate copy of the game. It does not work as a "crack" or a way around buying the game.

Managing instances and mods

The instance is the heart of Prism. Each instance is an independent folder with Minecraft: its own mods, settings, worlds, skins and game version.

Creating a new instance

Click Add Instance. You have several options:

• Vanilla: a clean Minecraft version: you pick the version (release, snapshot, old alpha/beta)
• Forge / NeoForge / Fabric / Quilt: created straight away with the mod loader of your choice, ready for mods
• Modrinth: browse and install official modpacks from modrinth.com
• CurseForge: import modpacks from CurseForge (needs an API key)
• Import from ZIP: install a modpack downloaded as a .mrpack or .zip archive

Adding mods

Right-click an instance → Edit → Mods. From there you can:

• Drag .jar files straight into the window to add them
• Download mods from Modrinth / CurseForge without leaving the launcher
• Enable / disable individual mods without deleting them
• Check for updates with one click

More about mod loaders: Forge guide, Fabric Loader guide.

Per-instance Java and RAM settings

Right-click an instance → Edit → Settings → Java. For instances with big modpacks (Better MC, All the Mods, RLCraft) set Maximum memory allocation: 6144 MB or more. For vanilla, 2048-3072 MB is enough. Prism can also pick the Java version that matches the Minecraft version automatically. The game needs Java 8 for 1.12, Java 17 for 1.18-1.20.4, Java 21 for 1.20.5-1.21.11 and Java 25 for 26.x versions (as of October 2026). If a 26.x instance does not start, check in this tab that it does not point to an older Java installation.

FAQ

Is Prism Launcher legal?

Yes. Prism Launcher requires you to sign in with a real Microsoft account that owns Minecraft. It does not bypass verification, does not let you play without buying the game and does not violate Mojang's terms of use. It is a fully legal alternative to the official launcher that the community has embraced.

Is Prism really open source?

Yes, all of the code is available on GitHub under the GPL-3.0 license. Anyone can see what the program does, report a bug or submit a fix. No ads, no hidden payments.

How is Prism different from MultiMC?

Prism is a 2022 fork of MultiMC. MultiMC still exists, but its development has slowed, while the Prism team adds new features faster (Modrinth integration, a better GUI, ARM support, current NeoForge). Both launchers work in a similar way: if you used MultiMC, you will switch without trouble, and Prism imports instances with one click.

Will servers see that I use Prism?

No. From the server's point of view the game looks identical to one started from the official launcher: it is the same game .jar file. Servers only see your username, the client version and optionally mods (if you use Forge/Fabric). The launcher has no effect on how the server sees you.

Does Prism support shaders and OptiFine?

Yes. You install OptiFine like any other mod: drag the .jar file into the mods list of a Forge instance. For shaders on Fabric, use Iris + Sodium. More: OptiFine guide.

Does Prism work with Bedrock Edition?

No. Prism is a launcher for Minecraft Java Edition only. Bedrock Edition (Windows 10, consoles, mobile) does not support custom launchers.