diff --git a/index.php b/index.php
index 55cb0a2..f755020 100644
--- a/index.php
+++ b/index.php
@@ -43,6 +43,48 @@ Flight::route("GET /polls/@id:[a-fA-F0-9]+", function ($id) {
 		Flight::notFound();
 });
 
+// POST /polls/:id/vote
+// Take an array of options and add a vote for each given option.
+Flight::route("POST /polls/@id:[a-fA-F0-9]+/vote", function ($id) {
+	$poll = Poll::load_poll($id);
+	if ($poll)
+	{
+		if (Flight::request()->type === "application/json")
+		{
+			if (isset(Flight::request()->data["options"]) && is_array(Flight::request()->data["options"]))
+			{ // Check that an options id array exists.
+				//TODO Check that only the authorized number of options are selected.
+				$poll->vote(Flight::request()->data["options"]); // Vote for the given options.
+				// Then save and show poll data.
+				$poll->save();
+				Flight::json(format_poll($poll));
+			}
+			else
+				Flight::halt(403, "<h1>403 Forbidden</h1><h3>Invalid data.</h3>");
+		}
+		else
+		{
+			if (isset(Flight::request()->data["options"]))
+			{ // Check that any data has been sent.
+				$selected_options = Flight::request()->data["options"];
+				if (is_string($selected_options))
+				{ // If it is a string, input[type="radio"] were used so only one option is selected.
+					$poll->vote([intval($selected_options)]); // Vote for the selected option.
+					$poll->save();
+					Flight::redirect("/polls/$id/results"); // Redirect to the results.
+				} //TODO: Multiple options case.
+				else
+					Flight::redirect("/polls/$id"); // Error: Redirect to the vote page.
+			}
+			else
+				Flight::redirect("/polls/$id"); // Error: Redirect to the vote page.
+			//TODO Error code in query parameters?
+		}
+	}
+	else
+		Flight::notFound();
+});
+
 Flight::route("/", function () {
 	global $VERLAINE;
 	Flight::render("home", ["app_url" => $VERLAINE["app_url"]], "body_content");
diff --git a/models/Poll.php b/models/Poll.php
index f2ae80b..55d7690 100644
--- a/models/Poll.php
+++ b/models/Poll.php
@@ -14,15 +14,12 @@ class Poll
 			$poll = new Poll();
 			$poll->title = $request_data->title;
 			$poll->creation_date = (new DateTime())->getTimestamp();
-			$id = 0;
 			foreach ($request_data->options as $option)
 			{
 				$poll->options[] = [
-					"id" => $id,
 					"label" => $option,
 					"votes" => 0,
 				];
-				$id++;
 			}
 			$poll->gen_new_id();
 			$poll->save();
@@ -80,6 +77,18 @@ class Poll
 		$this->id = $new_id;
 	}
 
+	/**
+	 * Vote for a list of options.
+	 * @param array $options - Array of integers containing voted options.
+	 */
+	public function vote(array $options)
+	{
+		// For each option in the list, add 1 to the vote number in the poll data.
+		foreach ($options as $option)
+			if (isset($this->options[intval($option)])) // Check invalid options id.
+				$this->options[intval($option)]->votes++;
+	}
+
 	public function save()
 	{
 		$db = dba_open(SAVE_PATH . "/polls.db", "wd");
diff --git a/views/poll.php b/views/poll.php
index 7fa4cb5..bf8e8f6 100644
--- a/views/poll.php
+++ b/views/poll.php
@@ -1,11 +1,11 @@
 <h1 class="poll"><?= $poll->title ?></h1>
 <main>
-  <form action="#" id="poll">
-    <?php foreach ($poll->options as $option): ?>
+  <form action="/polls/<?= $poll->id ?>/vote" method="POST" id="poll">
+    <?php foreach ($poll->options as $id => $option): ?>
     <div class="option">
-      <input type="radio" name="options" value="<?= $option->id ?>" id="option-<?= $option->id ?>" />
-      <label for="option-<?= $option->id ?>" class="check"></label>
-      <label for="option-<?= $option->id ?>"><?= $option->label ?></label>
+      <input type="radio" name="options" value="<?= $id ?>" id="option-<?= $id ?>" />
+      <label for="option-<?= $id ?>" class="check"></label>
+      <label for="option-<?= $id ?>"><?= $option->label ?></label>
     </div>
     <?php endforeach; ?>
     <input type="submit" value="Vote" />