diff --git a/elm.json b/elm.json
index 0a55772..5564502 100644
--- a/elm.json
+++ b/elm.json
@@ -6,13 +6,14 @@
     "elm-version": "0.19.0",
     "dependencies": {
         "direct": {
+            "NoRedInk/elm-json-decode-pipeline": "1.0.0",
             "elm/browser": "1.0.1",
             "elm/core": "1.0.2",
             "elm/html": "1.0.0",
+            "elm/json": "1.1.2",
             "elm/url": "1.0.0"
         },
         "indirect": {
-            "elm/json": "1.1.2",
             "elm/time": "1.0.0",
             "elm/virtual-dom": "1.0.2"
         }
diff --git a/src/Scylla/Sync.elm b/src/Scylla/Sync.elm
new file mode 100644
index 0000000..f312566
--- /dev/null
+++ b/src/Scylla/Sync.elm
@@ -0,0 +1,223 @@
+module Scylla.Sync exposing (..)
+import Dict exposing (Dict)
+import Json.Decode as Decode exposing (Decoder, int, string, float, list, value, dict, bool)
+import Json.Decode.Pipeline exposing (required, optional)
+
+-- General Events
+type alias Event =
+    { content : Decode.Value
+    , type_ : String
+    }
+
+eventDecoder : Decoder Event
+eventDecoder =
+    Decode.succeed Event
+        |> required "content" value
+        |> required "type" string
+
+type alias EventContent =
+    { avatarUrl : String
+    , displayname : String
+    , membership : String
+    , isDirect : Bool
+    -- , thirdPartyInvite : Invite
+    , unsigned : UnsignedData
+    }
+
+eventContentDecoder : Decoder EventContent
+eventContentDecoder =
+    Decode.succeed EventContent
+        |> required "avatar_url" string
+        |> required "displayname" string
+        |> required "membership" string
+        |> required "is_direct" bool
+        -- |> required "third_party_invite" inviteDecoder
+        |> required "unsigned" unsignedDataDecoder
+
+type alias State =
+    { events : List StateEvent
+    }
+
+-- Unsigned Data
+type alias UnsignedData =
+    { age : Int
+    , redactedBecause : Event
+    , transactionId : String
+    }
+
+unsignedDataDecoder : Decoder UnsignedData
+unsignedDataDecoder =
+    Decode.succeed UnsignedData
+        |> required "age" int
+        |> required "redacted_because" eventDecoder
+        |> required "transaction_id" string
+
+-- State
+stateDecoder : Decoder State
+stateDecoder =
+    Decode.succeed State
+        |> required "events" (list stateEventDecoder)
+
+type alias StateEvent =
+    { content : Decode.Value
+    , type_ : String
+    , eventId : String
+    , sender : String
+    , originServerTs : Int
+    , unsigned : UnsignedData
+    , prevContent : EventContent
+    , stateKey : String
+    }
+
+stateEventDecoder : Decoder StateEvent
+stateEventDecoder =
+    Decode.succeed StateEvent
+        |> required "required" value
+        |> required "type" string
+        |> required "event_id" string
+        |> required "sender" string
+        |> required "origin_server_ts" int
+        |> required "unsigned" unsignedDataDecoder
+        |> required "prev_content" eventContentDecoder
+        |> required "sate_key" string
+
+-- Rooms
+type alias Rooms =
+    { join : Dict String JoinedRoom
+    , invite : Dict String InvitedRoom
+    , leave : Dict String LeftRoom
+    }
+
+roomsDecoder : Decoder Rooms
+roomsDecoder =
+    Decode.succeed Rooms
+        |> required "join" (dict joinedRoomDecoder)
+        |> required "invite" (dict invitedRoomDecoder)
+        |> required "leave" (dict leftRoomDecoder)
+
+type alias JoinedRoom =
+    { state : State
+    , timeline : Timeline
+    , ephemeral : Ephemeral
+    , accountData : AccountData
+    , unreadNotifications : UnreadNotificationCounts
+    }
+
+joinedRoomDecoder : Decoder JoinedRoom
+joinedRoomDecoder =
+    Decode.succeed JoinedRoom
+        |> required "state" stateDecoder
+        |> required "timeline" timelineDecoder
+        |> required "ephemeral" ephemeralDecoder
+        |> required "account_data" accountDataDecoder
+        |> required "unread_notifications" unreadNotificationCountsDecoder
+
+
+--  Joined Room Data
+type alias Timeline =
+    { events : List RoomEvent
+    , limited : Bool
+    , prevBatch : String
+    }
+
+timelineDecoder =
+    Decode.succeed Timeline
+        |> required "events" (list roomEventDecoder)
+        |> required "limited" bool
+        |> required "prev_batch" string
+
+type alias RoomEvent =
+    { content : Decode.Value
+    , type_ : String
+    , eventId : String
+    , sender : String
+    , originServerTs : Int
+    , unsigned : UnsignedData
+    }
+
+roomEventDecoder : Decoder RoomEvent
+roomEventDecoder =
+    Decode.succeed RoomEvent
+        |> required "content" value
+        |> required "type" string
+        |> required "event_id" string
+        |> required "sender" string
+        |> required "origin_server_ts" int
+        |> required "unsigned" unsignedDataDecoder
+
+type alias Ephemeral =
+    { events : List Event
+    }
+
+ephemeralDecoder : Decoder Ephemeral
+ephemeralDecoder =
+    Decode.succeed Ephemeral
+        |> required "events" (list eventDecoder)
+
+type alias AccountData =
+    { events : List Event
+    }
+
+accountDataDecoder : Decoder AccountData
+accountDataDecoder =
+    Decode.succeed AccountData
+        |> required "events" (list eventDecoder)
+
+type alias UnreadNotificationCounts =
+    { highlightCount : Int
+    , notificationCount : Int
+    }
+
+unreadNotificationCountsDecoder : Decoder UnreadNotificationCounts
+unreadNotificationCountsDecoder =
+    Decode.succeed UnreadNotificationCounts
+        |> required "highlight_count" int
+        |> required "notification_count" int
+
+--  Invited Room Data
+type alias InvitedRoom =
+    { inviteState : InviteState
+    }
+
+invitedRoomDecoder : Decoder InvitedRoom
+invitedRoomDecoder =
+    Decode.succeed InvitedRoom
+        |> required "invite_state" inviteStateDecoder
+
+type alias InviteState =
+    { events : List StrippedState
+    }
+
+inviteStateDecoder : Decoder InviteState
+inviteStateDecoder =
+    Decode.succeed InviteState
+        |> required "events" (list strippedStateDecoder)
+
+type alias StrippedState =
+    { content : EventContent
+    , stateKey : String
+    , type_ : String
+    , sender : String
+    }
+
+strippedStateDecoder : Decoder StrippedState
+strippedStateDecoder =
+    Decode.succeed StrippedState
+        |> required "content" eventContentDecoder
+        |> required "state_key" string
+        |> required "type" string
+        |> required "sender" string
+
+-- Left Room Data
+type alias LeftRoom =
+    { state : State
+    , timeline : Timeline
+    , accountData : AccountData
+    }
+
+leftRoomDecoder : Decoder LeftRoom
+leftRoomDecoder =
+    Decode.succeed LeftRoom
+        |> required "state" stateDecoder
+        |> required "timeline" timelineDecoder
+        |> required "account_data" accountDataDecoder