diff --git a/nel/include/nel/misc/common.h b/nel/include/nel/misc/common.h
index 637c3c800..d9edc8e14 100644
--- a/nel/include/nel/misc/common.h
+++ b/nel/include/nel/misc/common.h
@@ -257,6 +257,8 @@ int compareCaseInsensitive(const char *a, const char *b);
 int compareCaseInsensitive(const char *a, size_t lenA, const char *b, size_t lenB);
 inline int compareCaseInsensitive(const std::string &a, const std::string &b) { return compareCaseInsensitive(&a[0], a.size(), &b[0], b.size()); }
 inline bool ltCaseInsensitive(const std::string &a, const std::string &b) { return compareCaseInsensitive(&a[0], a.size(), &b[0], b.size()) < 0; }
+std::string	toCaseInsensitive(const char *str); // UTF-8, case-insensitive toLower
+std::string	toCaseInsensitive(const std::string &str); // UTF-8, case-insensitive toLower
 
 /** ASCII to lowercase. Useful for internal identifiers.
 * Characters outside of the 7-bit ASCII space, and control characters, are replaced.
diff --git a/nel/src/misc/string_to_ci.cpp b/nel/src/misc/string_to_ci.cpp
index bdde3df23..1aeb36da2 100644
--- a/nel/src/misc/string_to_ci.cpp
+++ b/nel/src/misc/string_to_ci.cpp
@@ -2740,4 +2740,114 @@ int compareCaseInsensitive(const char *a, size_t lenA, const char *b, size_t len
 
 // ***************************************************************************
 
+NL_FORCE_INLINE void appendToCaseInsensitiveAsUtf8(std::string &res, const char *str, ptrdiff_t &i)
+{
+	unsigned char c = str[i];
+	unsigned char d, e, f;
+	if (c < 0x80)
+	{
+		if (c >= 'A' && c <= 'Z')
+		{
+			// 1-byte UTF-8
+			c += 'a' - 'A';
+		}
+	}
+	else if (c < 0xC0)
+	{
+		// non-starting byte
+	}
+	else if (c < 0xE0)
+	{
+		// 2-byte UTF-8
+		if (((d = str[i + 1]) & 0xC0) == 0x80)
+		{
+			const char *table = s_StringToCaseInsensitiveMap[c & 0x1F];
+			if (table)
+			{
+				unsigned char idx = (d & 0x3F) << 2;
+				if (table[idx])
+				{
+					res += &table[idx];
+					i += 2;
+					return;
+				}
+			}
+		}
+	}
+	else if (c < 0xF0)
+	{
+		// 3-byte UTF-8
+		if (((d = str[i + 1]) & 0xC0) == 0x80 && ((e = str[i + 2]) & 0xC0) == 0x80)
+		{
+			const char **map = s_StringToCaseInsensitiveMapMap[c & 0x0F];
+			if (map)
+			{
+				const char *table = map[d & 0x3F];
+				if (table)
+				{
+					unsigned char idx = (e & 0x3F) << 2;
+					if (table[idx])
+					{
+						res += &table[idx];
+						i += 3;
+						return;
+					}
+				}
+			}
+		}
+	}
+	else if (c < 0xF8)
+	{
+		// 4-byte UTF-8
+		if (((d = str[i + 1]) & 0xC0) == 0x80 && ((e = str[i + 2]) & 0xC0) == 0x80 && ((f = str[i + 3]) & 0xC0) == 0x80)
+		{
+			const char ***mapMap = s_StringToCaseInsensitiveMapMapMap[c & 0x07];
+			if (mapMap)
+			{
+				const char **map = mapMap[d & 0x3F];
+				if (map)
+				{
+					const char *table = map[e & 0x3F];
+					if (table)
+					{
+						unsigned char idx = (f & 0x3F) << 2;
+						if (table[idx])
+						{
+							res += &table[idx];
+							i += 4;
+							return;
+						}
+					}
+				}
+			}
+		}
+	}
+	res += c;
+	++i;
+}
+
+// ***************************************************************************
+
+std::string toCaseInsensitive(const char *str)
+{
+	// UTF-8 toCaseInsensitive
+	std::string res;
+	for (ptrdiff_t i = 0; str[i];)
+		appendToCaseInsensitiveAsUtf8(res, str, i);
+	return res;
+}
+
+// ***************************************************************************
+
+std::string	toCaseInsensitive(const std::string &str)
+{
+	// UTF-8 toCaseInsensitive
+	std::string res;
+	res.reserve(str.size() + (str.size() >> 2));
+	const char *cstr = &str[0];
+	for (ptrdiff_t i = 0; i < (ptrdiff_t)str.size();)
+		appendToCaseInsensitiveAsUtf8(res, cstr, i);
+	return res;
+}
+
 } // NLMISC
diff --git a/nel/src/misc/string_to_lower.cpp b/nel/src/misc/string_to_lower.cpp
index cd40abe88..d20dd015f 100644
--- a/nel/src/misc/string_to_lower.cpp
+++ b/nel/src/misc/string_to_lower.cpp
@@ -2530,7 +2530,7 @@ NL_FORCE_INLINE void appendToLowerAsUtf8(std::string &res, const char *str, ptrd
 
 std::string toLower(const char *str)
 {
-	// UTF-8 toLower, tables generated from UTF-16 tables
+	// UTF-8 toLower
 	std::string res;
 	for (ptrdiff_t i = 0; str[i];)
 		appendToLowerAsUtf8(res, str, i);
@@ -2541,7 +2541,7 @@ std::string toLower(const char *str)
 
 std::string	toLower(const std::string &str)
 {
-	// UTF-8 toLower, tables generated from UTF-16 tables
+	// UTF-8 toLower
 	std::string res;
 	res.reserve(str.size() + (str.size() >> 2));
 	const char *cstr = &str[0];
diff --git a/nel/src/misc/string_to_upper.cpp b/nel/src/misc/string_to_upper.cpp
index eb037969c..eefd0c6c6 100644
--- a/nel/src/misc/string_to_upper.cpp
+++ b/nel/src/misc/string_to_upper.cpp
@@ -2624,7 +2624,7 @@ static const char ***s_StringToUpperMapMapMap[8] = {
 
 std::string toUpper(const char *str)
 {
-	// UTF-8 toLower, tables generated from UTF-16 tables
+	// UTF-8 toLower
 	std::string res;
 	for (ptrdiff_t i = 0; str[i];)
 		appendToUpperAsUtf8(res, str, i);
@@ -2635,7 +2635,7 @@ std::string toUpper(const char *str)
 
 std::string	toUpper(const std::string &str)
 {
-	// UTF-8 toLower, tables generated from UTF-16 tables
+	// UTF-8 toLower
 	std::string res;
 	res.reserve(str.size() + (str.size() >> 2));
 	const char *cstr = &str[0];
diff --git a/ryzom/tools/leveldesign/uni_conv/uni_conv.cpp b/ryzom/tools/leveldesign/uni_conv/uni_conv.cpp
index d6afe9a57..554fc0f3d 100644
--- a/ryzom/tools/leveldesign/uni_conv/uni_conv.cpp
+++ b/ryzom/tools/leveldesign/uni_conv/uni_conv.cpp
@@ -17,6 +17,7 @@
 
 #include <nel/misc/types_nl.h>
 #include <nel/misc/ucstring.h>
+#include <nel/misc/utf_string_view.h>
 #include <nel/misc/common.h>
 #include <nel/misc/sstring.h>
 #include <nel/misc/i18n.h>
@@ -76,21 +77,10 @@ int main(int argc, char *argv[])
 	ucstring	str;
 	CI18N::readTextFile(inputFile, str, false, false);
 
-	if (outMode == ASCII)
-	{
-		// remove any outof ascii char
-		ucstring temp;
-		for (uint i=0; i<str.size(); ++i)
-		{
-			if (str[i] < 256)
-				temp += str[i];
-		}
-		str = temp;
-	}
-
 	if (xmlSupport)
 	{
 		ucstring temp;
+		temp.reserve(str.size());
 		for (uint i=0; i<str.size(); ++i)
 		{
 			switch(str[i])
@@ -121,9 +111,16 @@ int main(int argc, char *argv[])
 		break;
 	case ASCII:
 		{
-			string s = str.toString();
+			std::string res;
+			res.reserve(str.size());
+			for (ucstring::const_iterator it(str.begin()), end(str.end()); it != end; ++it)
+			{
+				ucchar c = *it;
+				if (c < 0x80)
+					res += (char)c;
+			}
 			FILE *fp = nlfopen(outputFile, "wt");
-			fwrite(s.data(), s.size(), 1, fp);
+			fwrite(res.data(), res.size(), 1, fp);
 			fclose(fp);
 		}
 		break;