diff --git a/packages/server/src/Tracker.js b/packages/server/src/Tracker.js
index b2af6d3..70ea7a8 100644
--- a/packages/server/src/Tracker.js
+++ b/packages/server/src/Tracker.js
@@ -39,6 +39,7 @@ class Tracker {
     this.identifiers = [];
     this.initializers = [];
     this.contextHandlers = [];
+    this.matcher = null;
 
     this.onIdentify = this.onIdentify.bind(this);
     this.onReconnect = this.onReconnect.bind(this);
@@ -49,6 +50,10 @@ class Tracker {
     this.api = api;
   }
 
+  onMatch(matcher) {
+    this.matcher = matcher;
+  }
+
   onIdent(cb) {
     return registerHandler(this.identifiers, cb);
   }
@@ -91,7 +96,7 @@ class Tracker {
       user = await this.identifiers.reduce((res, identifier) => {
         return res.then((identified) => {
           if (identified) return identified;
-          return identifier(ident);
+          return identifier(ident, params);
         });
       }, Promise.resolve(null));
     } catch (err) {
@@ -159,8 +164,13 @@ class Tracker {
     });
   }
 
-  match(url) {
-    return this.pattern.match(url);
+  match(url, req) {
+    const params = this.pattern.match(url);
+    if (!params || !this.matcher) return params;
+
+    const extraParams = this.matcher(req);
+    if (!extraParams) return false;
+    return Object.assign(params, extraParams);
   }
 }
 
diff --git a/packages/server/src/createServer.js b/packages/server/src/createServer.js
index a4f8159..00a1749 100644
--- a/packages/server/src/createServer.js
+++ b/packages/server/src/createServer.js
@@ -35,7 +35,7 @@ function createServer({ pulseRate = 30000, killTimeout = 1000 } = {}) {
     let reqParams = {};
 
     const tracker = trackers.find((t) => {
-      const params = t.match(request.url);
+      const params = t.match(request.url, request);
       if (!params) {
         return false;
       }