diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..3dafc56
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,3 @@
+.DS_Store
+
+tag2uti
\ No newline at end of file
diff --git a/Makefile b/Makefile
new file mode 100755
index 0000000..8d7c253
--- /dev/null
+++ b/Makefile
@@ -0,0 +1,18 @@
+#
+#  Copyright (c) 2019 rokudogobu
+#  
+#  Licensed under the Apache License, Version 2.0 (the "License");
+#  you may not use this file except in compliance with the License.
+#  You may obtain a copy of the License at
+#  
+#  http://www.apache.org/licenses/LICENSE-2.0
+#  
+#  Unless required by applicable law or agreed to in writing, software
+#  distributed under the License is distributed on an "AS IS" BASIS,
+#  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+#  See the License for the specific language governing permissions and
+#  limitations under the License.
+#
+
+tag2uti: main.c
+	clang -O2 -framework CoreFoundation -framework CoreServices -o $@ $^
diff --git a/README.md b/README.md
index 3763971..51a7ea1 100644
--- a/README.md
+++ b/README.md
@@ -1,2 +1,21 @@
+
 # tag2uti
-Simple C program to get UTI (= Uniform Type Identifier) from extension or MIME on Mac.
+
+Simple C program to get UTI (= Uniform Type Identifier) from filename extension or MIME type on Mac.
+
+## Usage
+
+    usage: tag2uti <ext | mime>...
+
+## Example
+
+    $ tag2uti c text/html bash
+    public.c-source
+    public.html
+    public.bash-script com.apple.xcode.bash-script
+
+## License
+
+Copyright (c) 2019 rokudogobu.  
+Licensed under the Apache License, Version 2.0.  
+See LICENSE for details.
diff --git a/main.c b/main.c
new file mode 100755
index 0000000..200b8e8
--- /dev/null
+++ b/main.c
@@ -0,0 +1,44 @@
+/*
+ 
+ Copyright (c) 2019 rokudogobu
+ 
+ Licensed under the Apache License, Version 2.0 (the "License");
+ you may not use this file except in compliance with the License.
+ You may obtain a copy of the License at
+ 
+ http://www.apache.org/licenses/LICENSE-2.0
+ 
+ Unless required by applicable law or agreed to in writing, software
+ distributed under the License is distributed on an "AS IS" BASIS,
+ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ See the License for the specific language governing permissions and
+ limitations under the License.
+ 
+ */
+ 
+#include <CoreFoundation/CoreFoundation.h>
+#include <CoreServices/CoreServices.h>
+
+#define STRENC kCFStringEncodingASCII
+
+int main( int argc, const char * argv[] ) {
+  for ( int i = 1; i < argc; i++ ) {
+    CFStringRef tag = CFStringCreateWithCString( kCFAllocatorDefault, argv[i], STRENC );
+    if ( tag ) {
+      CFRange     range = CFStringFind( tag, CFSTR( "/" ), 0 );
+      CFStringRef class = range.location == kCFNotFound ? kUTTagClassFilenameExtension: kUTTagClassMIMEType;
+      CFArrayRef  types = UTTypeCreateAllIdentifiersForTag( class, tag, NULL );
+      if ( types ) {
+        for ( int j = 0; j < CFArrayGetCount( types ); j++ ) {
+          printf( j == 0 ? "%s": " %s", CFStringGetCStringPtr( CFArrayGetValueAtIndex( types, j ), STRENC ));
+        }
+        CFRelease( types );
+      }
+      printf( "\n" );
+      CFRelease( tag );
+    }
+  }
+	return 0;
+}
+
+