diff --git a/src/formatitko/formatitko.py b/src/formatitko/formatitko.py
index e192c86..776d97e 100755
--- a/src/formatitko/formatitko.py
+++ b/src/formatitko/formatitko.py
@@ -29,12 +29,22 @@ def main():
 	parser.add_argument("-t", "--output-tex", help="The TEX file to write into.")
 	parser.add_argument("-m", "--output-md", help="The Markdown file to write into. (Uses pandoc to generate markdown)")
 	parser.add_argument("-j", "--output-json", help="The JSON file to dump the pandoc-compatible AST into.")
-	parser.add_argument("input_filename", help="The markdown file to process.")
+	parser.add_argument("--katex-server", action='store_true', help="Starts a KaTeX server and prints the socket filename onto stdout. Useful for running formatitko many times without starting the KaTeX server each time.")
+	parser.add_argument("-k", "--katex-socket", help="The KaTeX server socket filename obtained by running with `--katex-server`.")
+	parser.add_argument("input_filename", help="The markdown file to process.", nargs="?" if "--katex-server" in sys.argv else None)
 	parser.add_argument("--debug", action='store_true')
 	args = parser.parse_args()
-	# TODO: Accept path to unix socket for katexClient, then don't init our own,
-	# just connect to an existing one. For formátíking many files in a row.
 
+	if args.katex_server:
+		with KatexClient(connect=False) as katexClient:
+			print(katexClient.get_socket())
+			try:
+				while True:
+					pass
+			except KeyboardInterrupt:
+				print("Exiting...")
+				return
+	
 	# Use panflute to parse the input MD file
 	doc = import_md(open(args.input_filename, "r").read())
 
@@ -48,7 +58,7 @@ def main():
 
 	if args.output_html is not None:
 		# Initialize KaTeX client (this runs the node app and connects to a unix socket)
-		with KatexClient() as katexClient:
+		with KatexClient(socket=args.katex_socket) as katexClient:
 			HTMLGenerator(open(args.output_html, "w"), katexClient, imageProcessor).generate(doc)
 
 	if args.output_md is not None:
diff --git a/src/formatitko/katex-server/index.mjs b/src/formatitko/katex-server/index.mjs
index ecb4675..2c1c05c 100644
--- a/src/formatitko/katex-server/index.mjs
+++ b/src/formatitko/katex-server/index.mjs
@@ -83,7 +83,7 @@ async function handleClient(client) {
      * the one from the parent group and can add its own stuff without
      * affecting the parent.
      */
-    const macroStack = [{}]
+    let macroStack = [{}]
     for await (const line of rl) {
         try {
             // The custom commands for pushing and popping the macro stack.
@@ -94,6 +94,9 @@ async function handleClient(client) {
             } else if (line === "endgroup") {
                 macroStack.pop()
                 continue
+            } else if (line === "init") {
+                macroStack = [{}]
+                continue
             }
             const query = JSON.parse(line)
             const results = []
diff --git a/src/formatitko/katex.py b/src/formatitko/katex.py
index b0a3570..ad431e6 100644
--- a/src/formatitko/katex.py
+++ b/src/formatitko/katex.py
@@ -19,8 +19,21 @@ class KatexClient:
 	_server_process: subprocess.Popen[bytes]
 	_socket_file: str
 	_temp_dir: tempfile.TemporaryDirectory[str]
+	_connected: bool
 
-	def __init__(self):
+	def __init__(self, socket: str=None, connect: bool=True):
+		if socket is not None:
+			self._socket_file = socket
+		else:
+			self.open_socket()
+		if connect:
+			self.connect()
+			self._client.sendall("init\n".encode("utf-8")) # Reinitialize KaTeX Server in case it was reused.
+			self._connected = True
+		else:
+			self._connected = False
+
+	def open_socket(self):
 		# Create temporary directory for socket
 		self._temp_dir = tempfile.TemporaryDirectory(prefix='formatitko')
 		self._socket_file = self._temp_dir.name + "/katex-socket"
@@ -40,15 +53,20 @@ class KatexClient:
 
 		self._server_process = subprocess.Popen(["node", srcdir + "/katex-server/index.mjs", self._socket_file], stdout=subprocess.PIPE)
 
-		self._client = socket.socket(socket.AF_UNIX, socket.SOCK_STREAM)
-		
 		ok = self._server_process.stdout.readline()
 		if ok != b"OK\n":
 			raise KatexServerError("Failed to connect to katex-server")
 
+	def connect(self):
+		self._client = socket.socket(socket.AF_UNIX, socket.SOCK_STREAM)
 		self._client.connect(self._socket_file)
 
+	def get_socket(self):
+		return self._socket_file
+
 	def render(self, tex: str, options: dict={}):
+		if not self._connected:
+			raise KatexServerError("KatexClient not connected to Katex server. It should be initialized with connect=True.")
 		# Send formulas to translate
 		self._client.sendall((json.dumps({"formulas":[{"tex":tex}], "options":options})+"\n").encode("utf-8"))
 
@@ -67,13 +85,18 @@ class KatexClient:
 
 	# Special commands implemented in the JS file for grouping defs together.
 	def begingroup(self):
+		if not self._connected:
+			raise KatexServerError("KatexClient not connected to Katex server. It should be initialized with connect=True.")
 		self._client.sendall("begingroup\n".encode("utf-8"))
 
 	def endgroup(self):
+		if not self._connected:
+			raise KatexServerError("KatexClient not connected to Katex server. It should be initialized with connect=True.")
 		self._client.sendall("endgroup\n".encode("utf-8"))
 
 	def __enter__(self):
 		return self
 
 	def __exit__(self, type, value, tb):
-		self._server_process.terminate()
+		if hasattr(self, "_server_process") and self._server_process is not None:
+			self._server_process.terminate()