diff --git a/nise-backend/src/main/kotlin/com/nisemoe/nise/replays/Wtc.kt b/nise-backend/src/main/kotlin/com/nisemoe/nise/replays/Wtc.kt
new file mode 100644
index 0000000..b9fb3a9
--- /dev/null
+++ b/nise-backend/src/main/kotlin/com/nisemoe/nise/replays/Wtc.kt
@@ -0,0 +1,271 @@
+package com.nisemoe.nise.replays
+
+import java.io.ByteArrayOutputStream
+import java.nio.ByteBuffer
+import java.nio.ByteOrder
+import kotlin.math.abs
+import kotlin.math.round
+
+// JVM implementation of https://github.com/circleguard/wtc-lzma-compressor/tree/master
+
+private const val CURRENT_VERSION_HEADER: Short = 1
+
+private val VERSION_HEADER_BYTE_ARRAY = byteArrayOf((CURRENT_VERSION_HEADER.toInt() and 0xFF).toByte(), ((CURRENT_VERSION_HEADER.toInt() shr 8) and 0xFF).toByte())
+
+fun wtcCompress(stream: String): ByteArray {
+    val lists = seperate(stream)
+
+    val xs = unsortedDiffPackShortsToBytes(lists.x)
+    val ys = unsortedDiffPackShortsToBytes(lists.y)
+
+    val ws = packIntsToBytes(lists.w)
+    val zs = lists.z
+
+    fun packBytes(arr: ByteArray): ByteArray {
+        val length = arr.size
+        val buffer = ByteBuffer.allocate(4 + length).order(ByteOrder.LITTLE_ENDIAN)
+
+        buffer.putInt(length)
+        for (byte in arr) {
+            buffer.put(byte)
+        }
+
+        return buffer.array()
+    }
+
+    val byteStream = ByteArrayOutputStream()
+
+    byteStream.writeBytes(VERSION_HEADER_BYTE_ARRAY)
+    byteStream.writeBytes(packBytes(xs))
+    byteStream.writeBytes(packBytes(ys))
+    byteStream.writeBytes(packBytes(zs))
+    byteStream.writeBytes(packBytes(ws))
+
+    return byteStream.toByteArray()
+}
+
+fun wtcDecompress(data: ByteArray): String {
+    val buffer = ByteBuffer.wrap(data).order(ByteOrder.LITTLE_ENDIAN)
+
+    fun unpackBytes(): ByteArray {
+        val size = buffer.getInt()
+
+        val bytes = ByteArray(size)
+        buffer.get(bytes, 0, size)
+
+        return bytes
+    }
+
+    buffer.getShort() // Version - may be used in the future
+    val xs = unpackBytes()
+    val ys = unpackBytes()
+    val zs = unpackBytes()
+    val ws = unpackBytes()
+
+    val xxs = unsortedDiffUnpackBytesToShorts(xs)
+    val yys = unsortedDiffUnpackBytesToShorts(ys)
+
+    val wws = unpackBytesToInts(ws)
+
+    return combine(FrameLists(
+        x = xxs,
+        y = yys,
+        z = zs,
+        w = wws,
+    ))
+}
+
+data class FrameLists(
+    val x: ShortArray,
+    val y: ShortArray,
+    val z: ByteArray,
+    val w: IntArray,
+)
+
+private fun unsortedDiffPackShortsToBytes(shorts: ShortArray): ByteArray {
+    val start = shorts.first()
+    val diff = arrayDiff(shorts)
+    val packed = mutableListOf<Byte>()
+
+    fun pack(word: Short) {
+        if (abs(word.toInt()) <= Byte.MAX_VALUE) {
+            packed.add(word.toByte())
+        }
+        else {
+            packed.add(Byte.MIN_VALUE)
+            packed.add((word.toInt() and 0xFF).toByte())
+            packed.add((word.toInt() shr 8).toByte())
+        }
+    }
+
+    pack(start)
+    for (word in diff) {
+        pack(word)
+    }
+
+    return packed.toByteArray()
+}
+
+private fun unsortedDiffUnpackBytesToShorts(int8s: ByteArray): ShortArray {
+    val decoded = mutableListOf<Short>()
+
+    var i = 0
+    while (i < int8s.size) {
+        val byte = int8s[i]
+
+        if (byte == Byte.MIN_VALUE) {
+            i++
+            var word = int8s[i].toInt() and 0xFF
+            i++
+            word += int8s[i].toInt() shl 8
+            decoded.add(word.toShort())
+        }
+        else {
+            decoded.add(byte.toShort())
+        }
+
+        i++
+    }
+
+    return cumSum(decoded.toShortArray())
+}
+
+private fun packIntsToBytes(int32s: IntArray): ByteArray {
+    val packed = mutableListOf<Byte>()
+
+    for (dw in int32s) {
+        var dword = dw
+        if (abs(dword) <= Byte.MAX_VALUE) {
+            packed.add(dword.toByte())
+        }
+        else {
+            packed.add(Byte.MIN_VALUE)
+            packed.add((dword and 0xFF).toByte())
+            dword = dword shr 8
+            packed.add((dword and 0xFF).toByte())
+            dword = dword shr 8
+            packed.add((dword and 0xFF).toByte())
+            dword = dword shr 8
+            packed.add(dword.toByte())
+        }
+    }
+
+    return packed.toByteArray()
+}
+
+private fun unpackBytesToInts(int8s: ByteArray): IntArray {
+    val unpacked = mutableListOf<Int>()
+
+    var i = 0
+    while (i < int8s.size) {
+        val byte = int8s[i]
+
+        if (byte == Byte.MIN_VALUE) {
+            i++
+            var dword = int8s[i].toInt() and 0xFF
+            i++
+            dword += (int8s[i].toInt() shl 8) and 0xFF00
+            i++
+            dword += (int8s[i].toInt() shl 16) and 0xFF0000
+            i++
+            dword += int8s[i].toInt() shl 24
+            unpacked.add(dword)
+        }
+        else {
+            unpacked.add(byte.toInt())
+        }
+
+        i++
+    }
+
+    return unpacked.toIntArray()
+}
+
+private fun seperate(stream: String): FrameLists {
+    val wList = mutableListOf<Int>()
+    val xList = mutableListOf<Short>()
+    val yList = mutableListOf<Short>()
+    val zList = mutableListOf<Byte>()
+
+    for (frame in stream.split(",")) {
+        if (frame.isEmpty()) {
+            continue
+        }
+
+        val splitFrame = frame.split("|")
+        val w = splitFrame[0].toInt()
+        val x = splitFrame[1].toFloat()
+        val y = splitFrame[2].toFloat()
+        val z = splitFrame[3].toInt()
+
+        val zz = z and 0xFF
+
+        var xx = round(x * 16).toInt()
+        var yy = round(y * 16).toInt()
+
+        if (xx <= -0x8000) xx = -0x8000
+        else if (xx >= 0x7FFF) xx = 0x7FFF
+
+        if (yy <= -0x8000) yy = -0x8000
+        else if (yy >= 0x7FFF) yy = 0x7FFF
+
+        wList.add(w)
+        xList.add(xx.toShort())
+        yList.add(yy.toShort())
+        zList.add(zz.toByte())
+    }
+
+    return FrameLists(
+        x = xList.toShortArray(),
+        y = yList.toShortArray(),
+        z = zList.toByteArray(),
+        w = wList.toIntArray(),
+    )
+}
+
+private fun combine(lists: FrameLists): String {
+    val xArr = lists.x.map { it.toFloat() / 16 }
+
+    val yArr = lists.y.map { it.toFloat() / 16 }
+
+    val frames = arrayOfNulls<String>(xArr.size)
+
+    for (i in xArr.indices) {
+        val x = xArr[i]
+        val y = yArr[i]
+        val z = lists.z[i]
+        val w = lists.w[i]
+        frames[i] = "$w|$x|$y|$z"
+    }
+
+    return frames.joinToString(",")
+}
+
+private fun arrayDiff(arr: ShortArray): ShortArray {
+    if (arr.isEmpty()) {
+        return emptyArray<Short>().toShortArray()
+    }
+
+    val diffed = ShortArray(arr.size - 1)
+
+    for (index in 1..<arr.size) {
+        diffed[index - 1] = (arr[index] - arr[index - 1]).toShort()
+    }
+
+    return diffed
+}
+
+private fun cumSum(arr: ShortArray): ShortArray {
+    if (arr.isEmpty()) {
+        return emptyArray<Short>().toShortArray()
+    }
+
+    val cumArr = ShortArray(arr.size)
+
+    cumArr[0] = arr.first()
+    for (index in 1..<arr.size - 1) {
+        cumArr[index] = (arr[index] + cumArr[index - 1]).toShort()
+    }
+
+    return cumArr
+}
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