diff --git a/include/string_util.hpp b/include/string_util.hpp
new file mode 100644
index 0000000..7280251
--- /dev/null
+++ b/include/string_util.hpp
@@ -0,0 +1,20 @@
+#pragma once
+
+#ifndef PP_DEBUG
+#include <algorithm>
+#include <string>
+#endif
+
+inline void toLower(std::string &str) {
+    std::transform(str.begin(), str.end(), str.begin(),
+        [](unsigned char c){ return std::tolower(c); });
+}
+
+inline void toUpper(std::string &str) {
+    std::transform(str.begin(), str.end(), str.begin(),
+        [](unsigned char c){ return std::toupper(c); });
+}
+
+inline bool isInt(const std::string &str) {
+    return str.find_first_not_of("1234567890") == std::string::npos;
+}
diff --git a/src/osuparser.cpp b/src/osuparser.cpp
index cd82a89..235eb44 100644
--- a/src/osuparser.cpp
+++ b/src/osuparser.cpp
@@ -1,5 +1,7 @@
 #include <osuparser.hpp>
 
+#include <string_util.hpp>
+
 #ifndef PP_DEBUG
 #include <algorithm>
 #include <array>
@@ -23,11 +25,6 @@ inline std::string checkAndRemove(const std::string &str, const std::string &pre
     return trimString(str.substr(prefix.length()));
 }
 
-inline void toLower(std::string &str) {
-    std::transform(str.begin(), str.end(), str.begin(),
-        [](unsigned char c){ return std::tolower(c); });
-}
-
 #define CONFIG(name, ...) \
     name parse##name(fs::path configPath) {\
         if (!fs::exists(configPath)) {\