diff --git a/upload.sh b/upload.sh
index 539b10f..975863a 100755
--- a/upload.sh
+++ b/upload.sh
@@ -9,27 +9,82 @@ fi
 
 source ./upload.pwd
 
-LASTUPLOAD=`stat -c %Y upload.lasttime 2>/dev/null`
-if [[ -z $LASTUPLOAD ]]; then LASTUPLOAD=0; fi 
+if [ "$1" == "-h" ]; then
+	echo "Usage:"
+	echo "$0 -f filename [filename] ... -- upload specific files"
+	echo "$0 -n -- upload files whose moddates are later than last upload time"
+	echo ""
+	echo "By default, the program checks neocities for a list of files,"
+	echo "compares their sha1sums against ones in the out directory,"
+	echo "and uploads whichever files differ."
+	exit 0
+fi
 
 #echo "Last upload at $LASTUPLOAD"
 
-FILES=`find out/ -type f`
-
 UPFILES=()
 UPARGS=()
 
-for f in $FILES; do
-	MTIME=`stat -c %Y $f`
-	#echo "MTIME for $f: $MTIME"
-	if [[ $MTIME -gt $LASTUPLOAD ]]; then
-	  REMOTENAME="${f#out/}"
-	  echo "File $REMOTENAME needs uploading"
-	  UPFILES+=("$REMOTENAME")
-	  UPARGS+=("-F" "$REMOTENAME=@$f")
-	  #curl -F "$REMOTENAME=@$f" "https://$N_USER:$N_PWD@neocities.org/api/upload"
-	  fi
-done
+if [ "$1" == "-f" ]; then
+	
+	shift 
+	for f in "$@"; do
+	UPFILES+=("$f")
+	UPARGS+=("-F" "$f=@out/$f")
+	done
+elif [ "$1" == "-n" ]; then
+
+	LASTUPLOAD=`stat -c %Y upload.lasttime 2>/dev/null`
+	if [[ -z $LASTUPLOAD ]]; then LASTUPLOAD=0; fi 
+
+	FILES=`find out/ -type f -name '[!.]*'`
+
+	for f in $FILES; do
+		MTIME=`stat -c %Y $f`
+		#echo "MTIME for $f: $MTIME"
+		if [[ $MTIME -gt $LASTUPLOAD ]]; then
+		  REMOTENAME="${f#out/}"
+		  echo "File $REMOTENAME needs uploading"
+		  UPFILES+=("$REMOTENAME")
+		  UPARGS+=("-F" "$REMOTENAME=@$f")
+		  #curl -F "$REMOTENAME=@$f" "https://$N_USER:$N_PWD@neocities.org/api/upload"
+		  fi
+	done
+
+else
+
+	if ! command -v curl > /dev/null; then
+		echo "This program needs the 'curl' utility to perform HTTP requests."
+		exit 1
+	fi
+
+	if ! command -v jq > /dev/null; then
+		echo "This program needs the 'jq' utility to parse JSON outputs."
+		exit 1
+	fi
+
+	echo "Checking neocities for a file list..."
+	FILELIST=`curl -sS "https://$N_USER:$N_PWD@neocities.org/api/list"`
+
+	if [ `echo "$FILELIST" | jq -r ".result"` != 'success' ]; then
+		echo "Error while requesting file list."
+		echo "$FILELIST"
+		exit 1
+	fi
+
+	echo $FILELIST | jq -cr '.files[]|select(.is_directory == false)|[.sha1_hash,.path] | @tsv' | sed 's/\t/  /' | sort -k2 > remotehashes.txt
+
+	( cd out; find -name '[!.]*' * -type f -exec sha1sum {} + | sort -k2 ) > localhashes.txt
+
+	UPDFILES=`diff -U0 localhashes.txt remotehashes.txt | grep ^-[0-9a-f] | cut -d " " -f3`
+
+	for f in $UPDFILES; do
+		echo "* $f needs to be updated."
+		UPFILES+=("$f")
+		UPARGS+=("-F" "$f=@out/$f")
+	done
+
+fi
 
 if [[ ${#UPARGS[@]} -gt 0 ]]; then
 	curl ${UPARGS[@]} "https://$N_USER:$N_PWD@neocities.org/api/upload" && touch upload.lasttime