diff --git a/index.html b/index.html
index 9478307..2863776 100644
--- a/index.html
+++ b/index.html
@@ -62,9 +62,10 @@
             integrity="sha256-es+ex6Oj344uak+VnCPyaHY2nzQkqhr7ByWVQgdjATA=" crossorigin="anonymous"></script>
     <script>
         class NumeralSystem {
-            constructor(base, alphabet) {
+            constructor(base, alphabet, caseSensitive) {
                 this.base = base;
                 this.alphabet = alphabet;
+                this.caseSensitive = caseSensitive;
             }
 
 
@@ -73,11 +74,11 @@
             }
 
             baseToDecimal(baseString) {
-                return bigInt(baseString, this.base, this.alphabet);
+                return bigInt(baseString, this.base, this.alphabet, this.caseSensitive);
             }
 
             filterBaseString(baseString) {
-                return baseString.toLowerCase().replace(new RegExp("[^" + this.alphabet + "]"), "");
+                return baseString.replace(new RegExp("[^" + this.alphabet + "]"), "");
             }
         }
 
@@ -118,9 +119,9 @@
             new NumeralSystemInput("Binary", new NumeralSystem(2, "01")),
             new NumeralSystemInput("Octal", new NumeralSystem(8, "01234567")),
             new NumeralSystemInput("Decimal", new NumeralSystem(10, "0123456789")),
-            new NumeralSystemInput("Hexadecimal", new NumeralSystem(16, "0123456789abcdef")),
-            new NumeralSystemInput("Base64", new NumeralSystem(64, "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/")),
-            new NumeralSystemInput("ASCII", new NumeralSystem(256, new Array(256).fill(0).map((_, it) => String.fromCharCode(it)).join(""))),
+            new NumeralSystemInput("Hexadecimal", new NumeralSystem(16, "0123456789abcdef", caseSensitive = false)),
+            new NumeralSystemInput("Base64", new NumeralSystem(64, "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/", caseSensitive = true)),
+            new NumeralSystemInput("ASCII", new NumeralSystem(256, new Array(256).fill(0).map((_, it) => String.fromCharCode(it)).join(""), caseSensitive = true)),
         ];
 
         const updateAllInputs = newValue => {