diff --git a/src/__phutil_library_map__.php b/src/__phutil_library_map__.php
--- a/src/__phutil_library_map__.php
+++ b/src/__phutil_library_map__.php
@@ -394,6 +394,8 @@
     'PhutilRemarkupHeaderBlockRule' => 'markup/engine/remarkup/blockrule/PhutilRemarkupHeaderBlockRule.php',
     'PhutilRemarkupHighlightRule' => 'markup/engine/remarkup/markuprule/PhutilRemarkupHighlightRule.php',
     'PhutilRemarkupHorizontalRuleBlockRule' => 'markup/engine/remarkup/blockrule/PhutilRemarkupHorizontalRuleBlockRule.php',
+    'PhutilRemarkupHyperlinkEngineExtension' => 'markup/engine/remarkup/markuprule/PhutilRemarkupHyperlinkEngineExtension.php',
+    'PhutilRemarkupHyperlinkRef' => 'markup/engine/remarkup/markuprule/PhutilRemarkupHyperlinkRef.php',
     'PhutilRemarkupHyperlinkRule' => 'markup/engine/remarkup/markuprule/PhutilRemarkupHyperlinkRule.php',
     'PhutilRemarkupInlineBlockRule' => 'markup/engine/remarkup/blockrule/PhutilRemarkupInlineBlockRule.php',
     'PhutilRemarkupInterpreterBlockRule' => 'markup/engine/remarkup/blockrule/PhutilRemarkupInterpreterBlockRule.php',
@@ -1055,6 +1057,8 @@
     'PhutilRemarkupHeaderBlockRule' => 'PhutilRemarkupBlockRule',
     'PhutilRemarkupHighlightRule' => 'PhutilRemarkupRule',
     'PhutilRemarkupHorizontalRuleBlockRule' => 'PhutilRemarkupBlockRule',
+    'PhutilRemarkupHyperlinkEngineExtension' => 'Phobject',
+    'PhutilRemarkupHyperlinkRef' => 'Phobject',
     'PhutilRemarkupHyperlinkRule' => 'PhutilRemarkupRule',
     'PhutilRemarkupInlineBlockRule' => 'PhutilRemarkupBlockRule',
     'PhutilRemarkupInterpreterBlockRule' => 'PhutilRemarkupBlockRule',
diff --git a/src/markup/engine/remarkup/markuprule/PhutilRemarkupHyperlinkEngineExtension.php b/src/markup/engine/remarkup/markuprule/PhutilRemarkupHyperlinkEngineExtension.php
new file mode 100644
--- /dev/null
+++ b/src/markup/engine/remarkup/markuprule/PhutilRemarkupHyperlinkEngineExtension.php
@@ -0,0 +1,30 @@
+<?php
+
+abstract class PhutilRemarkupHyperlinkEngineExtension
+  extends Phobject {
+
+  private $engine;
+
+  final public function getHyperlinkEngineKey() {
+    return $this->getPhobjectClassConstant('LINKENGINEKEY', 32);
+  }
+
+  final public static function getAllLinkEngines() {
+    return id(new PhutilClassMapQuery())
+      ->setAncestorClass(__CLASS__)
+      ->setUniqueMethod('getHyperlinkEngineKey')
+      ->execute();
+  }
+
+  final public function setEngine(PhutilRemarkupEngine $engine) {
+    $this->engine = $engine;
+    return $this;
+  }
+
+  final public function getEngine() {
+    return $this->engine;
+  }
+
+  abstract public function processHyperlinks(array $hyperlinks);
+
+}
diff --git a/src/markup/engine/remarkup/markuprule/PhutilRemarkupHyperlinkRef.php b/src/markup/engine/remarkup/markuprule/PhutilRemarkupHyperlinkRef.php
new file mode 100644
--- /dev/null
+++ b/src/markup/engine/remarkup/markuprule/PhutilRemarkupHyperlinkRef.php
@@ -0,0 +1,38 @@
+<?php
+
+final class PhutilRemarkupHyperlinkRef
+  extends Phobject {
+
+  private $token;
+  private $uri;
+  private $embed;
+  private $result;
+
+  public function __construct(array $map) {
+    $this->token = $map['token'];
+    $this->uri = $map['uri'];
+    $this->embed = ($map['mode'] === '{');
+  }
+
+  public function getToken() {
+    return $this->token;
+  }
+
+  public function getURI() {
+    return $this->uri;
+  }
+
+  public function isEmbed() {
+    return $this->embed;
+  }
+
+  public function setResult($result) {
+    $this->result = $result;
+    return $this;
+  }
+
+  public function getResult() {
+    return $this->result;
+  }
+
+}
diff --git a/src/markup/engine/remarkup/markuprule/PhutilRemarkupHyperlinkRule.php b/src/markup/engine/remarkup/markuprule/PhutilRemarkupHyperlinkRule.php
--- a/src/markup/engine/remarkup/markuprule/PhutilRemarkupHyperlinkRule.php
+++ b/src/markup/engine/remarkup/markuprule/PhutilRemarkupHyperlinkRule.php
@@ -2,6 +2,8 @@
 
 final class PhutilRemarkupHyperlinkRule extends PhutilRemarkupRule {
 
+  const KEY_HYPERLINKS = 'hyperlinks';
+
   public function getPriority() {
     return 400.0;
   }
@@ -13,7 +15,13 @@
     // don't appear in normal text or normal URLs.
     $text = preg_replace_callback(
       '@<(\w{3,}://[^\s'.PhutilRemarkupBlockStorage::MAGIC_BYTE.']+?)>@',
-      array($this, 'markupHyperlink'),
+      array($this, 'markupHyperlinkAngle'),
+      $text);
+
+    // We match "{uri}", but do not link it by default.
+    $text = preg_replace_callback(
+      '@{(\w{3,}://[^\s'.PhutilRemarkupBlockStorage::MAGIC_BYTE.']+?)}@',
+      array($this, 'markupHyperlinkCurly'),
       $text);
 
     // Anything else we match "ungreedily", which means we'll look for
@@ -31,42 +39,49 @@
     return $text;
   }
 
-  protected function markupHyperlink(array $matches) {
+  public function markupHyperlinkAngle(array $matches) {
+    return $this->markupHyperlink('<', $matches);
+  }
+
+  public function markupHyperlinkCurly(array $matches) {
+    return $this->markupHyperlink('{', $matches);
+  }
+
+  protected function markupHyperlink($mode, array $matches) {
+    $raw_uri = $matches[1];
+
     try {
-      $uri = new PhutilURI($matches[1]);
+      $uri = new PhutilURI($raw_uri);
     } catch (Exception $ex) {
       return $matches[0];
     }
 
-    $protocol = $uri->getProtocol();
+    $engine = $this->getEngine();
 
-    $protocols = $this->getEngine()->getConfig(
-      'uri.allowed-protocols',
-      array());
+    $token = $engine->storeText($raw_uri);
 
-    if (!idx($protocols, $protocol)) {
-      // If this URI doesn't use a whitelisted protocol, don't link it. This
-      // is primarily intended to prevent javascript:// silliness.
-      return $this->getEngine()->storeText($matches[1]);
-    }
+    $list_key = self::KEY_HYPERLINKS;
+    $link_list = $engine->getTextMetadata($list_key, array());
 
-    return $this->storeRenderedHyperlink($matches[1]);
-  }
+    $link_list[] = array(
+      'token' => $token,
+      'uri' => $raw_uri,
+      'mode' => $mode,
+    );
 
-  protected function storeRenderedHyperlink($link) {
-    return $this->getEngine()->storeText($this->renderHyperlink($link));
-  }
+    $engine->setTextMetadata($list_key, $link_list);
 
-  protected function renderHyperlink($link) {
-    $engine = $this->getEngine();
+    return $token;
+  }
 
-    if ($engine->isTextMode()) {
-      return $link;
+  protected function renderHyperlink($link, $is_embed) {
+    // If the URI is "{uri}" and no handler picked it up, we just render it
+    // as plain text.
+    if ($is_embed) {
+      return $this->renderRawLink($link, $is_embed);
     }
 
-    if ($engine->getState('toc')) {
-      return $link;
-    }
+    $engine = $this->getEngine();
 
     $same_window = $engine->getConfig('uri.same-window', false);
     if ($same_window) {
@@ -86,6 +101,14 @@
       $link);
   }
 
+  private function renderRawLink($link, $is_embed) {
+    if ($is_embed) {
+      return '{'.$link.'}';
+    } else {
+      return $link;
+    }
+  }
+
   protected function markupHyperlinkUngreedy($matches) {
     $match = $matches[1];
     $tail = null;
@@ -116,7 +139,96 @@
       return $matches[0];
     }
 
-    return hsprintf('%s%s', $this->markupHyperlink(array(null, $match)), $tail);
+    $link = $this->markupHyperlink(null, array(null, $match));
+
+    return hsprintf('%s%s', $link, $tail);
+  }
+
+  public function didMarkupText() {
+    $engine = $this->getEngine();
+
+    $protocols = $engine->getConfig('uri.allowed-protocols', array());
+    $is_toc = $engine->getState('toc');
+    $is_text = $engine->isTextMode();
+    $is_mail = $engine->isHTMLMailMode();
+
+    $list_key = self::KEY_HYPERLINKS;
+    $raw_list = $engine->getTextMetadata($list_key, array());
+
+    $links = array();
+    foreach ($raw_list as $key => $link) {
+      $token = $link['token'];
+      $raw_uri = $link['uri'];
+      $mode = $link['mode'];
+
+      $is_embed = ($mode === '{');
+      $is_literal = ($mode === '<');
+
+      // If we're rendering in a "Table of Contents" or a plain text mode,
+      // we're going to render the raw URI without modifications.
+      if ($is_toc || $is_text) {
+        $result = $this->renderRawLink($raw_uri, $is_embed);
+        $engine->overwriteStoredText($token, $result);
+        continue;
+      }
+
+      // If this URI doesn't use a whitelisted protocol, don't link it. This
+      // is primarily intended to prevent "javascript://" silliness.
+      $uri = new PhutilURI($raw_uri);
+      $protocol = $uri->getProtocol();
+      $valid_protocol = idx($protocols, $protocol);
+      if (!$valid_protocol) {
+        $result = $this->renderRawLink($raw_uri, $is_embed);
+        $engine->overwriteStoredText($token, $result);
+        continue;
+      }
+
+      // If the URI is written as "<uri>", we'll render it literally even if
+      // some handler would otherwise deal with it.
+      // If we're rendering for HTML mail, we also render literally.
+      if ($is_literal || $is_mail) {
+        $result = $this->renderHyperlink($raw_uri, $is_embed);
+        $engine->overwriteStoredText($token, $result);
+        continue;
+      }
+
+      // Otherwise, this link is a valid resource which extensions are allowed
+      // to handle.
+      $links[$key] = $link;
+    }
+
+    if (!$links) {
+      return;
+    }
+
+    foreach ($links as $key => $link) {
+      $links[$key] = new PhutilRemarkupHyperlinkRef($link);
+    }
+
+    $extensions = PhutilRemarkupHyperlinkEngineExtension::getAllLinkEngines();
+    foreach ($extensions as $extension) {
+      $extension = id(clone $extension)
+        ->setEngine($engine)
+        ->processHyperlinks($links);
+
+      foreach ($links as $key => $link) {
+        $result = $link->getResult();
+        if ($result !== null) {
+          $engine->overwriteStoredText($link->getToken(), $result);
+          unset($links[$key]);
+        }
+      }
+
+      if (!$links) {
+        break;
+      }
+    }
+
+    // Render any remaining links in a normal way.
+    foreach ($links as $link) {
+      $result = $this->renderHyperlink($link->getURI(), $link->isEmbed());
+      $engine->overwriteStoredText($link->getToken(), $result);
+    }
   }
 
 }