diff --git a/README.md b/README.md
new file mode 100644
index 0000000..7004ae1
--- /dev/null
+++ b/README.md
@@ -0,0 +1,14 @@
+# CZI presence detector
+Tool to detect the presence of pre-defined devices by their WiFi MAC addresses.
+
+## How it works
+Sets the wifi adapter into monitor mode, then listens to surrounding packets listing all detected devices into `wifi_map.yaml`. Resets the wifi adapter to normal mode for uploading the results, filters the results by the mac addresses in `identities.yaml` and sends all matched identities to the front-end webhook server in `public`. This server stores the presence information locally and displays it with `public/index.php` with a timestamp of the last update.
+
+## Set-up
+Dependencies: Python3, trackerjacker (pip3), php (front-end)
+Configs to change:
+- wifi adapter in `scan.sh`
+- system-specific wifi commands in `scan.sh`
+- webhook URL and secret in `upload.py`
+- webhook secret in `public/update.php`
+- mac-name-identities in `identities.yaml`
\ No newline at end of file
diff --git a/public/index.php b/public/index.php
index c8bead5..5acd6bf 100644
--- a/public/index.php
+++ b/public/index.php
@@ -5,6 +5,9 @@ $present_file = 'present.json';
 
 $present = json_decode(file_get_contents($present_file), true);
 
+$tz = 'Europe/Berlin';
+$datetime = new DateTime("now", new DateTimeZone($tz));
+$datetime->setTimestamp($present["timestamp"]);
 
 ?>
 
@@ -22,7 +25,7 @@ $present = json_decode(file_get_contents($present_file), true);
       <span class="navbar-brand mb-0 h1" style="padding-left: 1rem"><?php echo $page_title; ?></span>
     </nav>
   <div id="content" style="padding: 2rem;">
-    <h2>Jetzt gerade im CZI <small>(letztes Update von <?php echo date('H:i:s d.m.Y', $present["timestamp"]); ?>)</small></h2><br>
+    <h2>Jetzt gerade im CZI <small>(letztes Update von <?php echo $datetime->format('H:i:s d.m.Y'); ?>)</small></h2><br>
     <table class="table">
       <thead>
         <tr>