diff --git a/src/HTTP/Requests/Request.php b/src/HTTP/Requests/Request.php
--- a/src/HTTP/Requests/Request.php
+++ b/src/HTTP/Requests/Request.php
@@ -7,5 +7,6 @@
 
     use WithAcceptedLanguages;
     use WithRemoteAddress;
+    use WithURL;
 
 }
diff --git a/src/HTTP/Requests/WithURL.php b/src/HTTP/Requests/WithURL.php
new file mode 100644
--- /dev/null
+++ b/src/HTTP/Requests/WithURL.php
@@ -0,0 +1,87 @@
+<?php
+
+namespace Keruald\OmniTools\HTTP\Requests;
+
+use Keruald\OmniTools\Strings\Multibyte\StringUtilities;
+
+trait WithURL {
+
+    ///
+    /// Main methods
+    ///
+
+    public static function getServerURL () : string {
+        $scheme = self::getScheme();
+        $name = self::getServerName();
+        $port = self::getPort();
+
+        // If we forward for a proxy, trust the scheme instead of standard :80
+        $fixToHTTPS = $port === 80 && $scheme === "https";
+
+        if ($port === 443 || $fixToHTTPS) {
+            return "https://$name";
+        }
+
+        if ($port === 80) {
+            return "http://$name";
+        }
+
+        return "$scheme://$name:$port";
+    }
+
+    ///
+    /// Helper methods
+    ///
+
+    public static function getPort () : int {
+        return (int)($_SERVER['SERVER_PORT'] ?? 80);
+    }
+
+    public static function getServerName () : string {
+        return $_SERVER['SERVER_NAME'] ?? "localhost";
+    }
+
+    public static function getScheme () : string {
+        return $_SERVER['REQUEST_SCHEME']
+            ?? $_SERVER['HTTP_X_FORWARDED_PROTO']
+            ?? $_SERVER['HTTP_X_FORWARDED_PROTOCOL']
+            ?? $_SERVER['HTTP_X_URL_SCHEME']
+            ?? self::guessScheme();
+    }
+
+    private static function guessScheme () : string {
+        return self::isHTTPS() ? "https" : "http";
+    }
+
+    public static function isHTTPS () : bool {
+        // Legacy headers have been documented at MDN:
+        // https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/X-Forwarded-Proto
+
+        $headers = self::getHTTPSHeadersTable();
+        foreach ($headers as $header => $value) {
+            if (isset($_SERVER[$header]) && $_SERVER[$header] === $value) {
+                return true;
+            }
+        }
+
+        if (isset($_SERVER['HTTP_FORWARDED'])) {
+            return StringUtilities::contains($_SERVER['HTTP_FORWARDED'], "proto=https");
+        }
+
+        return false;
+    }
+
+    private static function getHTTPSHeadersTable () : array {
+        return [
+            "HTTPS" => "on",
+            "REQUEST_SCHEME" => "https",
+            "SERVER_PORT" => "443",
+            "HTTP_X_FORWARDED_PROTO" => "https",
+            "HTTP_FRONT_END_HTTPS" => "on",
+            "HTTP_X_FORWARDED_PROTOCOL" => "https",
+            "HTTP_X_FORWARDED_SSL" => "on",
+            "HTTP_X_URL_SCHEME" => "https",
+        ];
+    }
+
+}
diff --git a/src/Strings/Multibyte/StringUtilities.php b/src/Strings/Multibyte/StringUtilities.php
--- a/src/Strings/Multibyte/StringUtilities.php
+++ b/src/Strings/Multibyte/StringUtilities.php
@@ -53,4 +53,8 @@
         return $length === 0 || mb_substr($string, -$length) === $end;
     }
 
+    public static function contains (string $string, string $needle) : bool {
+        return strpos($string, $needle) !== false;
+    }
+
 }
diff --git a/tests/HTTP/Requests/RequestTest.php b/tests/HTTP/Requests/RequestTest.php
--- a/tests/HTTP/Requests/RequestTest.php
+++ b/tests/HTTP/Requests/RequestTest.php
@@ -8,6 +8,10 @@
 
 class RequestTest extends TestCase {
 
+    ///
+    /// Tests
+    ///
+
     /**
      * @covers \Keruald\OmniTools\HTTP\Requests\Request::getRemoteAddress
      * @backupGlobals enabled
@@ -45,4 +49,69 @@
         );
     }
 
+    /**
+     * @backupGlobals enabled
+     * @dataProvider provideServerURLs
+     */
+    public function testGetServerURL (array $server, string $url) : void {
+        $_SERVER = $server;
+
+        $this->assertEquals($url, Request::getServerURL());
+    }
+
+    ///
+    /// Data providers
+    ///
+
+    public function provideServerURLs () : iterable {
+        yield [[], "http://localhost"];
+        yield [["UNRELATED" => "ANYTHING"], "http://localhost"];
+
+        yield [
+            [
+                "SERVER_PORT" => "80",
+                "SERVER_NAME" => "acme.tld",
+            ],
+            "http://acme.tld"
+        ];
+
+        yield [
+            [
+                "SERVER_PORT" => "443",
+                "SERVER_NAME" => "acme.tld",
+            ],
+            "https://acme.tld"
+        ];
+
+        yield [
+            [
+                "SERVER_PORT" => "80",
+                "SERVER_NAME" => "acme.tld",
+                "HTTP_X_FORWARDED_PROTO" => "https",
+            ],
+            "https://acme.tld"
+        ];
+
+        yield [
+            [
+                "SERVER_PORT" => "80",
+                "SERVER_NAME" => "acme.tld",
+                "HTTP_FORWARDED" => "for=192.0.2.43, for=\"[2001:db8:cafe::17]\", proto=https, by=203.0.113.43",
+            ],
+            "https://acme.tld"
+        ];
+
+        yield [
+            [
+                "SERVER_PORT" => "8443",
+                "SERVER_NAME" => "acme.tld",
+                "HTTPS" => "on",
+            ],
+            "https://acme.tld:8443"
+        ];
+
+
+    }
+
+
 }