diff --git a/pyproject.toml b/pyproject.toml
index 6877d24..03478e6 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -1,6 +1,7 @@
 [project]
 name = "stsg"
 dependencies = [
+    "watchdog~=6.0.0"
 ]
 dynamic = []
 authors = []
@@ -10,7 +11,8 @@ classifiers = []
 version = "0.0.0"
 
 [project.scripts]
-stsg_build = "stsg.__main__:main"
+stsg_build = "stsg.__main__:build"
+stsg_build_on_change = "stsg.__main__:build_on_change"
 
 
 [build-system]
diff --git a/stsg/__main__.py b/stsg/__main__.py
index cf11b36..2e11d8d 100644
--- a/stsg/__main__.py
+++ b/stsg/__main__.py
@@ -1,2 +1,45 @@
-def main():
-    print("main")
\ No newline at end of file
+import logging
+from watchdog.observers import Observer
+from watchdog.events import FileSystemEventHandler
+import time
+import os
+
+from .config import SOURCE_DIRECTORY
+
+
+logger = logging.getLogger("stsg")
+
+
+def build():
+    print("building")
+
+
+class CustomFileSystemEventHandler(FileSystemEventHandler):
+    def on_modified(self, event):
+        if event.is_directory:
+            return
+
+        filename = os.path.basename(event.src_path)
+        if filename.startswith('.') or filename.endswith(('~', '.tmp', '.swp')):
+            return
+
+        logger.info("%s changed, building", event.src_path)
+        build()
+
+
+
+def build_on_change():
+    print("build on change")
+    build()
+
+    observer = Observer()
+    observer.schedule(CustomFileSystemEventHandler(), path=SOURCE_DIRECTORY, recursive=True)
+    observer.start()
+
+
+    try:
+        while True:
+            time.sleep(1)  # Keeps the thread alive
+    except KeyboardInterrupt:
+        observer.stop()
+    observer.join()