diff --git a/src/string/str.c b/src/string/str.c
index fe3ee00..0d510cb 100644
--- a/src/string/str.c
+++ b/src/string/str.c
@@ -100,9 +100,26 @@ bool str_endsWith(str src, str fragment){
 
 u32 str_hash32(str s){
     u8* ubuf = (u8*)s.data;
-    u32 len = s.len;
     u32 hash=0;
-    for (u32 i = 0; i < len; i++)
+    for (u32 i = 0; i < s.len; i++)
         hash = (hash<<6) + (hash<<16) - hash + ubuf[i];
     return hash;
 }
+
+str str_toUpper(str src){
+    str r = str_copy(src);
+    for (u32 i = 0; i < r.len; i++){
+        if(isAlphabeticalLower(r.data[i]))
+            r.data[i] = r.data[i] - 'a' + 'A';
+    }
+    return r;
+}
+
+str str_toLower(str src){
+    str r = str_copy(src);
+    for (u32 i = 0; i < r.len; i++){
+        if(isAlphabeticalUpper(r.data[i]))
+            r.data[i] = r.data[i] - 'A' + 'a';
+    }
+    return r;
+}
diff --git a/src/string/str.h b/src/string/str.h
index 6db3c66..399bad5 100644
--- a/src/string/str.h
+++ b/src/string/str.h
@@ -36,3 +36,6 @@ bool str_endsWith(str src, str fragment);
 /// @brief calculates string hash using sdbm32 algorythm (something like lightweight crc32)
 /// @return non-cryptografic hash of the string
 u32 str_hash32(str s);
+
+str str_toUpper(str src);
+str str_toLower(str src);