diff --git a/js/converter.js b/js/converter.js
new file mode 100644
index 0000000..ac59a25
--- /dev/null
+++ b/js/converter.js
@@ -0,0 +1,63 @@
+// Hex → RGB
+export function hexToRgb(hex) {
+  const h = hex.replace('#', '');
+  const n = parseInt(h.length === 3
+    ? h.split('').map(c => c + c).join('')
+    : h, 16);
+  return { r: (n >> 16) & 255, g: (n >> 8) & 255, b: n & 255 };
+}
+
+// RGB → Hex
+export function rgbToHex({ r, g, b }) {
+  return '#' + [r, g, b].map(v => v.toString(16).padStart(2, '0')).join('');
+}
+
+// RGB → HSL (h: 0-360, s: 0-100, l: 0-100)
+export function rgbToHsl({ r, g, b }) {
+  r /= 255; g /= 255; b /= 255;
+  const max = Math.max(r, g, b), min = Math.min(r, g, b);
+  let h, s;
+  const l = (max + min) / 2;
+  if (max === min) {
+    h = s = 0;
+  } else {
+    const d = max - min;
+    s = l > 0.5 ? d / (2 - max - min) : d / (max + min);
+    switch (max) {
+      case r: h = ((g - b) / d + (g < b ? 6 : 0)) / 6; break;
+      case g: h = ((b - r) / d + 2) / 6; break;
+      case b: h = ((r - g) / d + 4) / 6; break;
+    }
+  }
+  return { h: Math.round(h * 360), s: Math.round(s * 100), l: Math.round(l * 100) };
+}
+
+// HSL → RGB
+export function hslToRgb({ h, s, l }) {
+  s /= 100; l /= 100;
+  const k = n => (n + h / 30) % 12;
+  const a = s * Math.min(l, 1 - l);
+  const f = n => l - a * Math.max(-1, Math.min(k(n) - 3, Math.min(9 - k(n), 1)));
+  return { r: Math.round(f(0) * 255), g: Math.round(f(8) * 255), b: Math.round(f(4) * 255) };
+}
+
+// HSL → Hex
+export function hslToHex(hsl) {
+  return rgbToHex(hslToRgb(hsl));
+}
+
+// Hex → HSL
+export function hexToHsl(hex) {
+  return rgbToHsl(hexToRgb(hex));
+}
+
+// Harmonien — Input: HSL, Output: Objekt mit Arrays von HSL-Objekten
+export function getHarmonies(hsl) {
+  const rotate = deg => ({ ...hsl, h: (hsl.h + deg + 360) % 360 });
+  return {
+    komplementaer:      [rotate(180)],
+    analog:             [rotate(-30), rotate(30)],
+    triade:             [rotate(120), rotate(240)],
+    splitKomplementaer: [rotate(150), rotate(210)],
+  };
+}