Ultimate Compression

Evidence

Ran on Kiln's test stand (2026-11-04): UltimateCompression did not start: java.lang.NoClassDefFoundError: net/minecraft/world/level/block/RotatedPillarBlock; UltimateCompressionClient did not start: java.lang.NoClassDefFoundError: net/minecraft/client/color/block/BlockTintSource.

What it needs from Kiln

• net.fabricmc.fabric.api.biome.v1.BiomeModifications
• net.fabricmc.fabric.api.biome.v1.BiomeSelectors
• net.fabricmc.fabric.api.client.rendering.v1.BlockColorRegistry
• net.fabricmc.fabric.api.event.lifecycle.v1.ServerTickEvents
• net.fabricmc.fabric.api.event.lifecycle.v1.ServerTickEvents.EndTick
• net.minecraft.client.color.block.BlockTintSource
• net.minecraft.client.renderer.BiomeColors
• net.minecraft.core.component.DataComponents
• net.minecraft.server.MinecraftServer
• net.minecraft.server.players.PlayerList
• net.minecraft.tags.BiomeTags
• net.minecraft.tags.BlockTags
• net.minecraft.tags.ItemTags
• net.minecraft.util.valueproviders.UniformInt
• net.minecraft.world.effect.MobEffectInstance
• net.minecraft.world.effect.MobEffects
• net.minecraft.world.entity.EquipmentSlot
• net.minecraft.world.item.CreativeModeTab.Builder
• net.minecraft.world.item.CreativeModeTab.DisplayItemsGenerator
• net.minecraft.world.item.CreativeModeTab.ItemDisplayParameters
• net.minecraft.world.item.CreativeModeTab.Output
• net.minecraft.world.item.CreativeModeTab.Row
• net.minecraft.world.item.ItemStackTemplate
• net.minecraft.world.item.ToolMaterial
• net.minecraft.world.item.component.CookingFuel
• net.minecraft.world.item.equipment.ArmorMaterial
• net.minecraft.world.item.equipment.ArmorType
• net.minecraft.world.item.equipment.EquipmentAssets
• net.minecraft.world.level.FoliageColor
• net.minecraft.world.level.block.DropExperienceBlock
• net.minecraft.world.level.block.FallingBlock
• net.minecraft.world.level.block.RotatedPillarBlock
• net.minecraft.world.level.block.state.BlockBehaviour.StateArgumentPredicate
• net.minecraft.world.level.block.state.BlockBehaviour.StatePredicate
• net.minecraft.world.level.levelgen.GenerationStep
• net.minecraft.world.level.levelgen.GenerationStep.Decoration
• net.minecraft.world.level.material.MapColor
• net.minecraft.world.level.storage.loot.providers.number.floats.ResolvableFloat
• net.minecraft.world.level.storage.loot.providers.number.floats.ResolvableFloat.Constant
• net.minecraft.world.level.storage.loot.providers.number.ints.ResolvableInt
• and 44 more

On the roadmap: Minecraft's libraries and client API (0.2), Code next to data (0.3)

In the author's words

Getting tired of the constant chest monsters and overflowing storage systems? Ultimate Compression is a mod created to reduce storage requirements by compressing almost all vanilla Minecraft blocks & items! The mod also includes custom tools and armor created with the compressed variants of ingots and their respective ores, with increased durability and effects.

Scan

Scanned on 4 November 2026 against Kiln 0.2.0, file ultimatecompression-26.3-3.5.0_fabric.jar. The scan reads the mod's classes; it does not run them.