MultiMC and OptiFine

Minecraft versions which have Forge

Just use OptiFine like any other Forge mod

Minecraft versions that don't have Forge

• Make a new instance in MultiMC with the wanted version of Minecraft.
• Click Edit Instance - it should open the Version page of the instance.
• Click Add Empty.
• Set uid to optifine.OptiFine and name to OptiFine.
• Select the newly created component and click Edit. It should open in a text editor. If it doesn't, make sure your operating system is set up to open .json files in one.
• Edit the JSON to look like one of the examples, then save the file. Most obvious mistakes will show up in the Version page.
• Download OptiFine and save the jar file in <Instance>/libraries/
• Launch the instance from MultiMC

If the example doesn't fit the OptiFine version exactly, you may have to change the versions in the file. For example replace all occurences of 1.7.10_HD_U_E3 with 1.7.10_HD_U_F1.

Examples

Minecraft 1.7.10

{
    "formatVersion": 1,
    "+libraries": [
        {
            "name": "net.minecraft:launchwrapper:1.12"
        },
        {
            "name": "optifine:OptiFine:1.7.10_HD_U_E3",
            "MMC-hint": "local",
            "MMC-filename": "OptiFine_1.7.10_HD_U_E3.jar"
        }
    ],
    "+tweakers": [ "optifine.OptiFineTweaker" ],
    "fileId": "optifine.OptiFine",
    "mainClass": "net.minecraft.launchwrapper.Launch",
    "requires": [
        {
            "uid": "net.minecraft",
            "equals": "1.7.10"
        }
    ],
    "name": "OptiFine",
    "version": "1.7.10_HD_U_E3"
}

Troubleshooting and FAQ

• java.lang.ClassDefNotFound: ...: make sure that the path to OptiFine that's outputted on the console is actually pointing to the file you downloaded.
• This broke my game!: You can always remove the patch and it's as if it was never there...