diff --git a/cache-550/build.gradle.kts b/cache-550/build.gradle.kts
new file mode 100644
index 00000000..52b6ba25
--- /dev/null
+++ b/cache-550/build.gradle.kts
@@ -0,0 +1,28 @@
+plugins {
+    `maven-publish`
+    kotlin("jvm")
+}
+
+dependencies {
+    api(projects.cache)
+
+    implementation(projects.buffer)
+    implementation(projects.util)
+}
+
+publishing {
+    publications.create<MavenPublication>("maven") {
+        from(components["java"])
+
+        pom {
+            packaging = "jar"
+            name.set("OpenRS2 Cache (Build 550)")
+            description.set(
+                """
+                A library for encoding and decoding files contained within the
+                RuneScape cache. It is only compatible with build 550.
+            """.trimIndent()
+            )
+        }
+    }
+}
diff --git a/cache-550/src/main/kotlin/org/openrs2/cache/config/enum/EnumType.kt b/cache-550/src/main/kotlin/org/openrs2/cache/config/enum/EnumType.kt
new file mode 100644
index 00000000..49b441ee
--- /dev/null
+++ b/cache-550/src/main/kotlin/org/openrs2/cache/config/enum/EnumType.kt
@@ -0,0 +1,100 @@
+package org.openrs2.cache.config.enum
+
+import io.netty.buffer.ByteBuf
+import it.unimi.dsi.fastutil.ints.Int2IntMap
+import it.unimi.dsi.fastutil.ints.Int2IntOpenHashMap
+import it.unimi.dsi.fastutil.ints.Int2ObjectMap
+import it.unimi.dsi.fastutil.ints.Int2ObjectOpenHashMap
+import org.openrs2.buffer.readString
+import org.openrs2.buffer.writeString
+import org.openrs2.cache.config.ConfigType
+import org.openrs2.util.charset.Cp1252Charset
+
+public class EnumType(id: Int) : ConfigType(id) {
+    public var keyType: Char = 0.toChar()
+    public var valueType: Char = 0.toChar()
+    public var defaultString: String = "null"
+    public var defaultInt: Int = 0
+
+    // TODO(gpe): methods for manipulating the maps
+    private var strings: Int2ObjectMap<String>? = null
+    private var ints: Int2IntMap? = null
+
+    override fun read(buf: ByteBuf, code: Int) {
+        when (code) {
+            1 -> keyType = Cp1252Charset.decode(buf.readByte())
+            2 -> valueType = Cp1252Charset.decode(buf.readByte())
+            3 -> defaultString = buf.readString()
+            4 -> defaultInt = buf.readInt()
+            5 -> {
+                val size = buf.readUnsignedShort()
+                val strings = Int2ObjectOpenHashMap<String>()
+
+                for (i in 0 until size) {
+                    val key = buf.readInt()
+                    strings[key] = buf.readString()
+                }
+
+                this.strings = strings
+            }
+            6 -> {
+                val size = buf.readUnsignedShort()
+                val ints = Int2IntOpenHashMap()
+
+                for (i in 0 until size) {
+                    val key = buf.readInt()
+                    ints[key] = buf.readInt()
+                }
+
+                this.ints = ints
+            }
+            else -> throw IllegalArgumentException("Unsupported config code: $code")
+        }
+    }
+
+    override fun write(buf: ByteBuf) {
+        if (keyType.code != 0) {
+            buf.writeByte(1)
+            buf.writeByte(Cp1252Charset.encode(keyType).toInt())
+        }
+
+        if (valueType.code != 0) {
+            buf.writeByte(2)
+            buf.writeByte(Cp1252Charset.encode(valueType).toInt())
+        }
+
+        if (defaultString != "null") {
+            buf.writeByte(3)
+            buf.writeString(defaultString)
+        }
+
+        if (defaultInt != 0) {
+            buf.writeByte(4)
+            buf.writeInt(defaultInt)
+        }
+
+        val strings = strings
+        if (strings != null && strings.isNotEmpty()) {
+            buf.writeByte(5)
+            buf.writeShort(strings.size)
+
+            for ((key, value) in strings.int2ObjectEntrySet()) {
+                buf.writeInt(key)
+                buf.writeString(value)
+            }
+        }
+
+        val ints = ints
+        if (ints != null && ints.isNotEmpty()) {
+            buf.writeByte(6)
+            buf.writeShort(ints.size)
+
+            for ((key, value) in ints.int2IntEntrySet()) {
+                buf.writeInt(key)
+                buf.writeInt(value)
+            }
+        }
+
+        buf.writeByte(0)
+    }
+}
diff --git a/cache-550/src/main/kotlin/org/openrs2/cache/config/enum/EnumTypeList.kt b/cache-550/src/main/kotlin/org/openrs2/cache/config/enum/EnumTypeList.kt
new file mode 100644
index 00000000..446bc4fe
--- /dev/null
+++ b/cache-550/src/main/kotlin/org/openrs2/cache/config/enum/EnumTypeList.kt
@@ -0,0 +1,15 @@
+package org.openrs2.cache.config.enum
+
+import org.openrs2.cache.Cache
+import org.openrs2.cache.Js5Archive
+import org.openrs2.cache.config.ArchiveConfigTypeList
+
+public class EnumTypeList(cache: Cache) : ArchiveConfigTypeList<EnumType>(
+    cache,
+    archive = Js5Archive.CONFIG_ENUM,
+    fileBits = 8
+) {
+    override fun allocate(id: Int): EnumType {
+        return EnumType(id)
+    }
+}
diff --git a/cache-550/src/main/kotlin/org/openrs2/cache/config/param/ParamType.kt b/cache-550/src/main/kotlin/org/openrs2/cache/config/param/ParamType.kt
new file mode 100644
index 00000000..27c2a82b
--- /dev/null
+++ b/cache-550/src/main/kotlin/org/openrs2/cache/config/param/ParamType.kt
@@ -0,0 +1,42 @@
+package org.openrs2.cache.config.param
+
+import io.netty.buffer.ByteBuf
+import org.openrs2.buffer.readString
+import org.openrs2.buffer.writeString
+import org.openrs2.cache.config.ConfigType
+import org.openrs2.util.charset.Cp1252Charset
+
+public class ParamType(id: Int) : ConfigType(id) {
+    public var type: Char = 0.toChar()
+    public var defaultInt: Int = 0
+    public var defaultString: String? = null
+
+    override fun read(buf: ByteBuf, code: Int) {
+        when (code) {
+            1 -> type = Cp1252Charset.decode(buf.readByte())
+            2 -> defaultInt = buf.readInt()
+            5 -> defaultString = buf.readString()
+            else -> throw IllegalArgumentException("Unsupported config code: $code")
+        }
+    }
+
+    override fun write(buf: ByteBuf) {
+        if (type.code != 0) {
+            buf.writeByte(1)
+            buf.writeByte(Cp1252Charset.encode(type).toInt())
+        }
+
+        if (defaultInt != 0) {
+            buf.writeByte(2)
+            buf.writeInt(defaultInt)
+        }
+
+        val defaultString = defaultString
+        if (defaultString != null) {
+            buf.writeByte(5)
+            buf.writeString(defaultString)
+        }
+
+        buf.writeByte(0)
+    }
+}
diff --git a/cache-550/src/main/kotlin/org/openrs2/cache/config/param/ParamTypeList.kt b/cache-550/src/main/kotlin/org/openrs2/cache/config/param/ParamTypeList.kt
new file mode 100644
index 00000000..b49062eb
--- /dev/null
+++ b/cache-550/src/main/kotlin/org/openrs2/cache/config/param/ParamTypeList.kt
@@ -0,0 +1,16 @@
+package org.openrs2.cache.config.param
+
+import org.openrs2.cache.Cache
+import org.openrs2.cache.Js5Archive
+import org.openrs2.cache.Js5ConfigGroup
+import org.openrs2.cache.config.GroupConfigTypeList
+
+public class ParamTypeList(cache: Cache) : GroupConfigTypeList<ParamType>(
+    cache,
+    archive = Js5Archive.CONFIG,
+    group = Js5ConfigGroup.PARAMTYPE
+) {
+    override fun allocate(id: Int): ParamType {
+        return ParamType(id)
+    }
+}
diff --git a/cache-550/src/main/kotlin/org/openrs2/cache/config/struct/StructType.kt b/cache-550/src/main/kotlin/org/openrs2/cache/config/struct/StructType.kt
new file mode 100644
index 00000000..cdc550eb
--- /dev/null
+++ b/cache-550/src/main/kotlin/org/openrs2/cache/config/struct/StructType.kt
@@ -0,0 +1,57 @@
+package org.openrs2.cache.config.struct
+
+import io.netty.buffer.ByteBuf
+import it.unimi.dsi.fastutil.ints.Int2ObjectMap
+import it.unimi.dsi.fastutil.ints.Int2ObjectOpenHashMap
+import org.openrs2.buffer.readString
+import org.openrs2.buffer.writeString
+import org.openrs2.cache.config.ConfigType
+
+public class StructType(id: Int) : ConfigType(id) {
+    // TODO(gpe): methods for manipulating the map
+    private val params: Int2ObjectMap<Any> = Int2ObjectOpenHashMap()
+
+    override fun read(buf: ByteBuf, code: Int) {
+        when (code) {
+            249 -> {
+                val size = buf.readUnsignedByte().toInt()
+                for (i in 0 until size) {
+                    val string = buf.readBoolean()
+                    val id = buf.readUnsignedMedium()
+
+                    if (string) {
+                        params[id] = buf.readString()
+                    } else {
+                        params[id] = buf.readInt()
+                    }
+                }
+            }
+            else -> throw IllegalArgumentException("Unsupported config code: $code")
+        }
+    }
+
+    override fun write(buf: ByteBuf) {
+        if (params.isNotEmpty()) {
+            buf.writeByte(249)
+            buf.writeByte(params.size)
+
+            for ((id, value) in params.int2ObjectEntrySet()) {
+                when (value) {
+                    is String -> {
+                        buf.writeBoolean(true)
+                        buf.writeMedium(id)
+                        buf.writeString(value)
+                    }
+                    is Int -> {
+                        buf.writeBoolean(false)
+                        buf.writeMedium(id)
+                        buf.writeInt(value)
+                    }
+                    else -> throw IllegalStateException()
+                }
+            }
+        }
+
+        buf.writeByte(0)
+    }
+}
diff --git a/cache-550/src/main/kotlin/org/openrs2/cache/config/struct/StructTypeList.kt b/cache-550/src/main/kotlin/org/openrs2/cache/config/struct/StructTypeList.kt
new file mode 100644
index 00000000..13574c52
--- /dev/null
+++ b/cache-550/src/main/kotlin/org/openrs2/cache/config/struct/StructTypeList.kt
@@ -0,0 +1,16 @@
+package org.openrs2.cache.config.struct
+
+import org.openrs2.cache.Cache
+import org.openrs2.cache.Js5Archive
+import org.openrs2.cache.Js5ConfigGroup
+import org.openrs2.cache.config.GroupConfigTypeList
+
+public class StructTypeList(cache: Cache) : GroupConfigTypeList<StructType>(
+    cache,
+    archive = Js5Archive.CONFIG,
+    group = Js5ConfigGroup.STRUCTTYPE
+) {
+    override fun allocate(id: Int): StructType {
+        return StructType(id)
+    }
+}
diff --git a/cache-550/src/main/kotlin/org/openrs2/cache/config/varbit/VarbitType.kt b/cache-550/src/main/kotlin/org/openrs2/cache/config/varbit/VarbitType.kt
new file mode 100644
index 00000000..e60d7ed8
--- /dev/null
+++ b/cache-550/src/main/kotlin/org/openrs2/cache/config/varbit/VarbitType.kt
@@ -0,0 +1,32 @@
+package org.openrs2.cache.config.varbit
+
+import io.netty.buffer.ByteBuf
+import org.openrs2.cache.config.ConfigType
+
+public class VarbitType(id: Int) : ConfigType(id) {
+    public var baseVar: Int = 0
+    public var startBit: Int = 0
+    public var endBit: Int = 0
+
+    override fun read(buf: ByteBuf, code: Int) {
+        when (code) {
+            1 -> {
+                baseVar = buf.readUnsignedShort()
+                startBit = buf.readUnsignedByte().toInt()
+                endBit = buf.readUnsignedByte().toInt()
+            }
+            else -> throw IllegalArgumentException("Unsupported config code: $code")
+        }
+    }
+
+    override fun write(buf: ByteBuf) {
+        if (baseVar != 0 || startBit != 0 || endBit != 0) {
+            buf.writeByte(1)
+            buf.writeShort(baseVar)
+            buf.writeByte(startBit)
+            buf.writeByte(endBit)
+        }
+
+        buf.writeByte(0)
+    }
+}
diff --git a/cache-550/src/main/kotlin/org/openrs2/cache/config/varbit/VarbitTypeList.kt b/cache-550/src/main/kotlin/org/openrs2/cache/config/varbit/VarbitTypeList.kt
new file mode 100644
index 00000000..70d408db
--- /dev/null
+++ b/cache-550/src/main/kotlin/org/openrs2/cache/config/varbit/VarbitTypeList.kt
@@ -0,0 +1,15 @@
+package org.openrs2.cache.config.varbit
+
+import org.openrs2.cache.Cache
+import org.openrs2.cache.Js5Archive
+import org.openrs2.cache.config.ArchiveConfigTypeList
+
+public class VarbitTypeList(cache: Cache) : ArchiveConfigTypeList<VarbitType>(
+    cache,
+    archive = Js5Archive.CONFIG_VAR_BIT,
+    fileBits = 10
+) {
+    override fun allocate(id: Int): VarbitType {
+        return VarbitType(id)
+    }
+}
diff --git a/cache-550/src/main/kotlin/org/openrs2/cache/config/varp/VarpType.kt b/cache-550/src/main/kotlin/org/openrs2/cache/config/varp/VarpType.kt
new file mode 100644
index 00000000..92695b05
--- /dev/null
+++ b/cache-550/src/main/kotlin/org/openrs2/cache/config/varp/VarpType.kt
@@ -0,0 +1,24 @@
+package org.openrs2.cache.config.varp
+
+import io.netty.buffer.ByteBuf
+import org.openrs2.cache.config.ConfigType
+
+public class VarpType(id: Int) : ConfigType(id) {
+    public var clientCode: Int = 0
+
+    override fun read(buf: ByteBuf, code: Int) {
+        when (code) {
+            5 -> clientCode = buf.readUnsignedShort()
+            else -> throw IllegalArgumentException("Unsupported config code: $code")
+        }
+    }
+
+    override fun write(buf: ByteBuf) {
+        if (clientCode != 0) {
+            buf.writeByte(5)
+            buf.writeShort(clientCode)
+        }
+
+        buf.writeByte(0)
+    }
+}
diff --git a/cache-550/src/main/kotlin/org/openrs2/cache/config/varp/VarpTypeList.kt b/cache-550/src/main/kotlin/org/openrs2/cache/config/varp/VarpTypeList.kt
new file mode 100644
index 00000000..ecb3cd00
--- /dev/null
+++ b/cache-550/src/main/kotlin/org/openrs2/cache/config/varp/VarpTypeList.kt
@@ -0,0 +1,16 @@
+package org.openrs2.cache.config.varp
+
+import org.openrs2.cache.Cache
+import org.openrs2.cache.Js5Archive
+import org.openrs2.cache.Js5ConfigGroup
+import org.openrs2.cache.config.GroupConfigTypeList
+
+public class VarpTypeList(cache: Cache) : GroupConfigTypeList<VarpType>(
+    cache,
+    archive = Js5Archive.CONFIG,
+    group = Js5ConfigGroup.VAR_PLAYER
+) {
+    override fun allocate(id: Int): VarpType {
+        return VarpType(id)
+    }
+}
diff --git a/settings.gradle.kts b/settings.gradle.kts
index b77cc734..e16b720d 100644
--- a/settings.gradle.kts
+++ b/settings.gradle.kts
@@ -31,6 +31,7 @@ include(
     "buffer",
     "buffer-generator",
     "cache",
+    "cache-550",
     "cli",
     "compress",
     "compress-cli",