diff --git a/ws/frame.nim b/ws/frame.nim
index 10e46d1..5055a69 100644
--- a/ws/frame.nim
+++ b/ws/frame.nim
@@ -55,7 +55,7 @@ template remainder*(frame: Frame): uint64 =
 proc encode*(
   frame: Frame,
   offset = 0,
-  extensions: seq[Extension] = @[]): Future[seq[byte]] {.async.} =
+  extensions: seq[Ext] = @[]): Future[seq[byte]] {.async.} =
   ## Encodes a frame into a string buffer.
   ## See https://tools.ietf.org/html/rfc6455#section-5.2
 
@@ -117,7 +117,7 @@ proc decode*(
   _: typedesc[Frame],
   reader: AsyncStreamReader,
   masked: bool,
-  extensions: seq[Extension] = @[]): Future[Frame] {.async.} =
+  extensions: seq[Ext] = @[]): Future[Frame] {.async.} =
   ## Read and Decode incoming header
   ##
 
diff --git a/ws/session.nim b/ws/session.nim
index 7f36680..c9830a4 100644
--- a/ws/session.nim
+++ b/ws/session.nim
@@ -61,7 +61,7 @@ proc send*(
         mask: ws.masked,
         data: data, # allow sending data with close messages
         maskKey: maskKey)
-        .encode()))
+        .encode(extensions = ws.extensions)))
 
     return
 
@@ -212,7 +212,8 @@ proc readFrame*(ws: WSSession): Future[Frame] {.async.} =
   ##
 
   while ws.readyState != ReadyState.Closed:
-    let frame = await Frame.decode(ws.stream.reader, ws.masked)
+    let frame = await Frame.decode(
+      ws.stream.reader, ws.masked, ws.extensions)
     debug "Decoded new frame", opcode = frame.opcode, len = frame.length, mask = frame.mask
 
     # return the current frame if it's not one of the control frames
diff --git a/ws/types.nim b/ws/types.nim
index 8dc08aa..26729f8 100644
--- a/ws/types.nim
+++ b/ws/types.nim
@@ -9,6 +9,7 @@
 
 {.push raises: [Defect].}
 
+import std/tables
 import pkg/[chronos, chronos/streams/tlsstream]
 import ./utils
 
@@ -89,11 +90,15 @@ type
   CloseCb* = proc(code: Status, reason: string):
     CloseResult {.gcsafe, raises: [Defect].}
 
-  Extension* = ref object of RootObj
+  Ext* = ref object of RootObj
     name*: string
+    options*: Table[string, string]
+
+  ExtFactory* = proc(name: string, options: Table[string, string]):
+    Ext {.raises: [Defect].}
 
   WebSocket* = ref object of RootObj
-    extensions: seq[Extension] # extension active for this session
+    extensions*: seq[Ext]
     version*: uint
     key*: string
     readyState*: ReadyState
@@ -127,11 +132,14 @@ type
   WSInvalidOpcodeError* = object of WebSocketError
   WSInvalidUTF8* = object of WebSocketError
 
-proc `name=`*(self: Extension, name: string) =
+proc `name=`*(self: Ext, name: string) =
   raiseAssert "Can't change extensions name!"
 
-method decode*(self: Extension, frame: Frame): Future[Frame] {.base, async.} =
+method decode*(self: Ext, frame: Frame): Future[Frame] {.base, async.} =
   raiseAssert "Not implemented!"
 
-method encode*(self: Extension, frame: Frame): Future[Frame] {.base, async.} =
+method encode*(self: Ext, frame: Frame): Future[Frame] {.base, async.} =
+  raiseAssert "Not implemented!"
+
+method toHttpOptions*(self: Ext): string =
   raiseAssert "Not implemented!"
diff --git a/ws/ws.nim b/ws/ws.nim
index 280ced2..c2017ec 100644
--- a/ws/ws.nim
+++ b/ws/ws.nim
@@ -35,6 +35,7 @@ export utils, session, frame, types, http
 type
   WSServer* = ref object of WebSocket
     protocols: seq[string]
+    factories: seq[ExtFactory]
 
 func toException(e: string): ref WebSocketError =
   (ref WebSocketError)(msg: e)
@@ -46,6 +47,7 @@ proc connect*(
   _: type WebSocket,
   uri: Uri,
   protocols: seq[string] = @[],
+  extensions: seq[Ext] = @[],
   flags: set[TLSFlags] = {},
   version = WSDefaultVersion,
   frameSize = WSDefaultFrameSize,
@@ -105,6 +107,7 @@ proc connect*(
     stream: client.stream,
     readyState: ReadyState.Open,
     masked: true,
+    extensions: @extensions,
     rng: rng,
     frameSize: frameSize,
     onPing: onPing,
@@ -116,6 +119,7 @@ proc connect*(
   address: TransportAddress,
   path: string,
   protocols: seq[string] = @[],
+  extensions: seq[Ext] = @[],
   secure = false,
   flags: set[TLSFlags] = {},
   version = WSDefaultVersion,
@@ -142,6 +146,7 @@ proc connect*(
   return await WebSocket.connect(
     uri = parseUri(uri),
     protocols = protocols,
+    extensions = extensions,
     flags = flags,
     version = version,
     frameSize = frameSize,
@@ -155,6 +160,7 @@ proc connect*(
   port: Port,
   path: string,
   protocols: seq[string] = @[],
+  extensions: seq[Ext] = @[],
   secure = false,
   flags: set[TLSFlags] = {},
   version = WSDefaultVersion,
@@ -168,6 +174,7 @@ proc connect*(
     address = initTAddress(host, port),
     path = path,
     protocols = protocols,
+    extensions = extensions,
     flags = flags,
     version = version,
     frameSize = frameSize,
@@ -253,11 +260,11 @@ proc handleRequest*(
 proc new*(
   _: typedesc[WSServer],
   protos: openArray[string] = [""],
+  factories: openArray[ExtFactory] = [],
   frameSize = WSDefaultFrameSize,
   onPing: ControlCb = nil,
   onPong: ControlCb = nil,
   onClose: CloseCb = nil,
-  extensions: openArray[Extension] = [],
   rng: Rng = nil): WSServer =
 
   return WSServer(
@@ -265,6 +272,7 @@ proc new*(
     masked: false,
     rng: if isNil(rng): newRng() else: rng,
     frameSize: frameSize,
+    factories: @factories,
     onPing: onPing,
     onPong: onPong,
     onClose: onClose)