diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..f9d5764
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,2 @@
+__pycache__/
+.*
diff --git a/config.py b/config.py
new file mode 100644
index 0000000..5d7a0c9
--- /dev/null
+++ b/config.py
@@ -0,0 +1,6 @@
+imgdir = "."
+recursive = True
+refresh = 5
+cachedir = "auto"
+resolution = (1920, 1080)
+filetypes = ["*.jpg", "*.JPG"]
diff --git a/requirements.txt b/requirements.txt
index f2e1e50..2d2ba95 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -1 +1,4 @@
 Flask==1.0.2
+Pillow==5.3.0
+Click==7.0
+waitress==1.1.0
diff --git a/server.py b/server.py
new file mode 100755
index 0000000..8acd373
--- /dev/null
+++ b/server.py
@@ -0,0 +1,7 @@
+#!/usr/bin/python3
+
+from waitress import serve
+
+import slider
+
+serve(slider.app, host="0.0.0.0", port=5000)
diff --git a/slider.py b/slider.py
index db343c8..6090ec8 100755
--- a/slider.py
+++ b/slider.py
@@ -1,15 +1,127 @@
 #!/usr/bin/python3
 
-from flask import Flask, render_template
-from random import randint
+from flask import (
+    Flask,
+    render_template,
+    send_from_directory,
+    redirect,
+    url_for,
+    request,
+)
+from random import choice
+from pathlib import Path
+from PIL import Image
+from time import time
+from hashlib import sha256
+import click
+from shutil import rmtree
+from tempfile import gettempdir
+
+import config
 
 app = Flask(__name__)
 
+imgdir = Path(config.imgdir).expanduser().resolve()
+cache_resolution = config.resolution
+cache_dir = (
+    Path(gettempdir()) / "webslider"
+    if config.cachedir == "auto"
+    else Path(config.cachedir)
+) / ("%sx%s" % cache_resolution)
+
+
+def find_images():
+    images = set()
+    for filetype in config.filetypes:
+        glob = "**/" + filetype if config.recursive else filetype
+        images.update(imgdir.glob(glob))
+    return list(images)
+
 
 @app.route("/")
-def hello():
-    return render_template("hello.html", num=randint(1, 23))
+def random():
+    print(request.remote_addr, request.base_url)
+    return render_template("random.html", refresh=config.refresh)
+
+
+@app.route("/random_image/")
+def random_image():
+    print(request.remote_addr, request.base_url)
+    try:
+        last_modified_time, last_modified_file = max(
+            (f.stat().st_mtime, f) for f in find_images()
+        )
+
+        if time() - last_modified_time <= 60:
+            selected_image = last_modified_file.relative_to(imgdir)
+        else:
+            images = find_images()
+            selected_image = choice(images).relative_to(imgdir)
+    except ValueError:
+        return redirect(url_for("static", filename="clear.gif"))
+
+    return redirect(
+        url_for("image", filename=selected_image)
+        + "?hash=%s" % get_cache_filename(selected_image)
+    )
+
+
+@app.route("/img/<path:filename>")
+def image(filename):
+    print(request.remote_addr, request.base_url)
+    cache_filename = create_cache_file(filename)
+
+    return send_from_directory(cache_dir, cache_filename)
+
+
+def rm_cachedir():
+    if cache_dir.exists():
+        print("Removing cache dir", cache_dir)
+        rmtree(cache_dir)
+
+
+def create_cachedir():
+    if not cache_dir.exists():
+        print("Creating cache dir", cache_dir)
+        cache_dir.mkdir(parents=True)
+
+
+def create_cache_file(filename):
+    create_cachedir()
+    cache_file = get_cache_filename(filename)
+
+    if not (cache_dir / cache_file).exists():
+        print("Creating cache file", filename)
+        img = Image.open(imgdir / filename)
+        img.thumbnail(cache_resolution)
+        img.save(cache_dir / cache_file, "JPEG")
+
+    return cache_file
+
+
+def get_cache_filename(filename):
+    original_file_path = imgdir / filename
+    return sha256(str(original_file_path.resolve()).encode("utf-8")).hexdigest()
+
+
+def pre_cache_images():
+    for image_file in sorted(find_images()):
+        create_cache_file(image_file.relative_to(imgdir))
+
+
+@click.command()
+@click.option("--build-cache", is_flag=True, default=False, help="pre-cache images")
+@click.option(
+    "--clear-cache", is_flag=True, default=False, help="clear cache directory"
+)
+def run_slider(build_cache, clear_cache):
+    if clear_cache:
+        rm_cachedir()
+    if build_cache:
+        pre_cache_images()
+
+    app.run(host="0.0.0.0")
 
 
 if __name__ == "__main__":
-    app.run()
+    run_slider()
diff --git a/static/clear.gif b/static/clear.gif
new file mode 100755
index 0000000..f55d454
Binary files /dev/null and b/static/clear.gif differ
diff --git a/static/loading.gif b/static/loading.gif
new file mode 100755
index 0000000..d0bce15
Binary files /dev/null and b/static/loading.gif differ
diff --git a/templates/hello.html b/templates/hello.html
deleted file mode 100644
index 77172c2..0000000
--- a/templates/hello.html
+++ /dev/null
@@ -1,6 +0,0 @@
-<html>
-<body>
-	<p>Hello slider number {{ num }}!</p>
-	<p><img src="{{ url_for("static", filename="cat.jpg") }}"></p>
-</body>
-</html>
diff --git a/templates/random.html b/templates/random.html
new file mode 100644
index 0000000..e612e38
--- /dev/null
+++ b/templates/random.html
@@ -0,0 +1,30 @@
+<html>
+	<head>
+	<style>
+		img {
+			width: 100%;
+			height: 98%;
+			object-fit: contain;
+			background: url({{ url_for("static", filename="loading.gif") }}) 50% no-repeat;
+		}
+	</style>
+	</head>
+	<body bgcolor="black">
+		<img id="slider" src="{{ url_for("static", filename="clear.gif") }}" />
+		<script>
+			var downloadingImage = new Image();
+			downloadingImage.onload = function()
+			{
+				document.getElementById("slider").src = this.src;
+			};
+
+			function updateImage() 
+			{
+				downloadingImage.src = "{{ url_for("random_image") }}?" + new Date().getTime();
+			}
+
+			updateImage();
+			setInterval(updateImage, {{ refresh * 1000 }});
+		</script>
+	</body>
+</html>