diff --git a/openpype/__init__.py b/openpype/__init__.py
index 11b563ebfe..9175727a54 100644
--- a/openpype/__init__.py
+++ b/openpype/__init__.py
@@ -10,8 +10,9 @@ from .lib import (
     Anatomy,
     filter_pyblish_plugins,
     set_plugin_attributes_from_settings,
-    change_timer_to_current_context
+    change_timer_to_current_context,
 )
+from .pipeline import register_event_callback
 
 pyblish = avalon = _original_discover = None
 
@@ -122,10 +123,10 @@ def install():
     avalon.discover = patched_discover
     pipeline.discover = patched_discover
 
-    avalon.on("taskChanged", _on_task_change)
+    register_event_callback("taskChanged", _on_task_change)
 
 
-def _on_task_change(*args):
+def _on_task_change():
     change_timer_to_current_context()
 
 
diff --git a/openpype/hosts/aftereffects/api/pipeline.py b/openpype/hosts/aftereffects/api/pipeline.py
index 94f1e3d105..6f7cd8c46d 100644
--- a/openpype/hosts/aftereffects/api/pipeline.py
+++ b/openpype/hosts/aftereffects/api/pipeline.py
@@ -10,6 +10,7 @@ from avalon import io, pipeline
 from openpype import lib
 from openpype.api import Logger
 import openpype.hosts.aftereffects
+from openpype.pipeline import register_event_callback
 
 from .launch_logic import get_stub
 
@@ -73,7 +74,7 @@ def install():
         "instanceToggled", on_pyblish_instance_toggled
     )
 
-    avalon.api.on("application.launched", application_launch)
+    register_event_callback("application.launched", application_launch)
 
 
 def uninstall():
diff --git a/openpype/hosts/blender/api/pipeline.py b/openpype/hosts/blender/api/pipeline.py
index 6da0ba3dcb..38312316cc 100644
--- a/openpype/hosts/blender/api/pipeline.py
+++ b/openpype/hosts/blender/api/pipeline.py
@@ -15,6 +15,10 @@ from avalon import io, schema
 from avalon.pipeline import AVALON_CONTAINER_ID
 
 from openpype.api import Logger
+from openpype.pipeline import (
+    register_event_callback,
+    emit_event
+)
 import openpype.hosts.blender
 
 HOST_DIR = os.path.dirname(os.path.abspath(openpype.hosts.blender.__file__))
@@ -50,8 +54,9 @@ def install():
 
     lib.append_user_scripts()
 
-    avalon.api.on("new", on_new)
-    avalon.api.on("open", on_open)
+    register_event_callback("new", on_new)
+    register_event_callback("open", on_open)
+
     _register_callbacks()
     _register_events()
 
@@ -113,22 +118,22 @@ def set_start_end_frames():
     scene.render.resolution_y = resolution_y
 
 
-def on_new(arg1, arg2):
+def on_new():
     set_start_end_frames()
 
 
-def on_open(arg1, arg2):
+def on_open():
     set_start_end_frames()
 
 
 @bpy.app.handlers.persistent
 def _on_save_pre(*args):
-    avalon.api.emit("before_save", args)
+    emit_event("before.save")
 
 
 @bpy.app.handlers.persistent
 def _on_save_post(*args):
-    avalon.api.emit("save", args)
+    emit_event("save")
 
 
 @bpy.app.handlers.persistent
@@ -136,9 +141,9 @@ def _on_load_post(*args):
     # Detect new file or opening an existing file
     if bpy.data.filepath:
         # Likely this was an open operation since it has a filepath
-        avalon.api.emit("open", args)
+        emit_event("open")
     else:
-        avalon.api.emit("new", args)
+        emit_event("new")
 
     ops.OpenFileCacher.post_load()
 
@@ -169,7 +174,7 @@ def _register_callbacks():
     log.info("Installed event handler _on_load_post...")
 
 
-def _on_task_changed(*args):
+def _on_task_changed():
     """Callback for when the task in the context is changed."""
 
     # TODO (jasper): Blender has no concept of projects or workspace.
@@ -186,7 +191,7 @@ def _on_task_changed(*args):
 def _register_events():
     """Install callbacks for specific events."""
 
-    avalon.api.on("taskChanged", _on_task_changed)
+    register_event_callback("taskChanged", _on_task_changed)
     log.info("Installed event callback for 'taskChanged'...")
 
 
diff --git a/openpype/hosts/harmony/api/pipeline.py b/openpype/hosts/harmony/api/pipeline.py
index 17d2870876..a94d30210e 100644
--- a/openpype/hosts/harmony/api/pipeline.py
+++ b/openpype/hosts/harmony/api/pipeline.py
@@ -9,6 +9,7 @@ import avalon.api
 from avalon.pipeline import AVALON_CONTAINER_ID
 
 from openpype import lib
+from openpype.pipeline import register_event_callback
 import openpype.hosts.harmony
 import openpype.hosts.harmony.api as harmony
 
@@ -129,7 +130,7 @@ def check_inventory():
     harmony.send({"function": "PypeHarmony.message", "args": msg})
 
 
-def application_launch():
+def application_launch(event):
     """Event that is executed after Harmony is launched."""
     # FIXME: This is breaking server <-> client communication.
     # It is now moved so it it manually called.
@@ -187,7 +188,7 @@ def install():
         "instanceToggled", on_pyblish_instance_toggled
     )
 
-    avalon.api.on("application.launched", application_launch)
+    register_event_callback("application.launched", application_launch)
 
 
 def uninstall():
diff --git a/openpype/hosts/hiero/api/events.py b/openpype/hosts/hiero/api/events.py
index 7563503593..6e2580ed8c 100644
--- a/openpype/hosts/hiero/api/events.py
+++ b/openpype/hosts/hiero/api/events.py
@@ -1,7 +1,7 @@
 import os
 import hiero.core.events
-import avalon.api as avalon
 from openpype.api import Logger
+from openpype.pipeline import register_event_callback
 from .lib import (
     sync_avalon_data_to_workfile,
     launch_workfiles_app,
@@ -126,5 +126,5 @@ def register_events():
     """
 
     # if task changed then change notext of hiero
-    avalon.on("taskChanged", update_menu_task_label)
+    register_event_callback("taskChanged", update_menu_task_label)
     log.info("Installed event callback for 'taskChanged'..")
diff --git a/openpype/hosts/hiero/api/menu.py b/openpype/hosts/hiero/api/menu.py
index 306bef87ca..de20b86f30 100644
--- a/openpype/hosts/hiero/api/menu.py
+++ b/openpype/hosts/hiero/api/menu.py
@@ -14,7 +14,7 @@ self = sys.modules[__name__]
 self._change_context_menu = None
 
 
-def update_menu_task_label(*args):
+def update_menu_task_label():
     """Update the task label in Avalon menu to current session"""
 
     object_name = self._change_context_menu
diff --git a/openpype/hosts/houdini/api/pipeline.py b/openpype/hosts/houdini/api/pipeline.py
index 1c08e72d65..86c85ad3a1 100644
--- a/openpype/hosts/houdini/api/pipeline.py
+++ b/openpype/hosts/houdini/api/pipeline.py
@@ -11,6 +11,10 @@ import avalon.api
 from avalon.pipeline import AVALON_CONTAINER_ID
 from avalon.lib import find_submodule
 
+from openpype.pipeline import (
+    register_event_callback,
+    emit_event
+)
 import openpype.hosts.houdini
 from openpype.hosts.houdini.api import lib
 
@@ -51,11 +55,11 @@ def install():
     avalon.api.register_plugin_path(avalon.api.Creator, CREATE_PATH)
 
     log.info("Installing callbacks ... ")
-    # avalon.on("init", on_init)
-    avalon.api.before("save", before_save)
-    avalon.api.on("save", on_save)
-    avalon.api.on("open", on_open)
-    avalon.api.on("new", on_new)
+    # register_event_callback("init", on_init)
+    register_event_callback("before.save", before_save)
+    register_event_callback("save", on_save)
+    register_event_callback("open", on_open)
+    register_event_callback("new", on_new)
 
     pyblish.api.register_callback(
         "instanceToggled", on_pyblish_instance_toggled
@@ -101,13 +105,13 @@ def _register_callbacks():
 
 def on_file_event_callback(event):
     if event == hou.hipFileEventType.AfterLoad:
-        avalon.api.emit("open", [event])
+        emit_event("open")
     elif event == hou.hipFileEventType.AfterSave:
-        avalon.api.emit("save", [event])
+        emit_event("save")
     elif event == hou.hipFileEventType.BeforeSave:
-        avalon.api.emit("before_save", [event])
+        emit_event("before_save")
     elif event == hou.hipFileEventType.AfterClear:
-        avalon.api.emit("new", [event])
+        emit_event("new")
 
 
 def get_main_window():
@@ -229,11 +233,11 @@ def ls():
         yield data
 
 
-def before_save(*args):
+def before_save():
     return lib.validate_fps()
 
 
-def on_save(*args):
+def on_save():
 
     log.info("Running callback on save..")
 
@@ -242,7 +246,7 @@ def on_save(*args):
         lib.set_id(node, new_id, overwrite=False)
 
 
-def on_open(*args):
+def on_open():
 
     if not hou.isUIAvailable():
         log.debug("Batch mode detected, ignoring `on_open` callbacks..")
@@ -279,7 +283,7 @@ def on_open(*args):
             dialog.show()
 
 
-def on_new(_):
+def on_new():
     """Set project resolution and fps when create a new file"""
 
     if hou.hipFile.isLoadingHipFile():
diff --git a/openpype/hosts/maya/api/pipeline.py b/openpype/hosts/maya/api/pipeline.py
index 1b3bb9feb3..05db1b7b26 100644
--- a/openpype/hosts/maya/api/pipeline.py
+++ b/openpype/hosts/maya/api/pipeline.py
@@ -2,7 +2,6 @@ import os
 import sys
 import errno
 import logging
-import contextlib
 
 from maya import utils, cmds, OpenMaya
 import maya.api.OpenMaya as om
@@ -16,6 +15,10 @@ from avalon.pipeline import AVALON_CONTAINER_ID
 import openpype.hosts.maya
 from openpype.tools.utils import host_tools
 from openpype.lib import any_outdated
+from openpype.pipeline import (
+    register_event_callback,
+    emit_event
+)
 from openpype.lib.path_tools import HostDirmap
 from openpype.hosts.maya.lib import copy_workspace_mel
 from . import menu, lib
@@ -55,7 +58,7 @@ def install():
     log.info(PUBLISH_PATH)
 
     log.info("Installing callbacks ... ")
-    avalon.api.on("init", on_init)
+    register_event_callback("init", on_init)
 
     # Callbacks below are not required for headless mode, the `init` however
     # is important to load referenced Alembics correctly at rendertime.
@@ -69,12 +72,12 @@ def install():
 
     menu.install()
 
-    avalon.api.on("save", on_save)
-    avalon.api.on("open", on_open)
-    avalon.api.on("new", on_new)
-    avalon.api.before("save", on_before_save)
-    avalon.api.on("taskChanged", on_task_changed)
-    avalon.api.on("before.workfile.save", before_workfile_save)
+    register_event_callback("save", on_save)
+    register_event_callback("open", on_open)
+    register_event_callback("new", on_new)
+    register_event_callback("before.save", on_before_save)
+    register_event_callback("taskChanged", on_task_changed)
+    register_event_callback("before.workfile.save", before_workfile_save)
 
 
 def _set_project():
@@ -137,7 +140,7 @@ def _register_callbacks():
 
 
 def _on_maya_initialized(*args):
-    avalon.api.emit("init", args)
+    emit_event("init")
 
     if cmds.about(batch=True):
         log.warning("Running batch mode ...")
@@ -147,16 +150,16 @@ def _on_maya_initialized(*args):
     lib.get_main_window()
 
 
-def _on_scene_new(*args):
-    avalon.api.emit("new", args)
+def _on_scene_new():
+    emit_event("new")
 
 
-def _on_scene_save(*args):
-    avalon.api.emit("save", args)
+def _on_scene_save():
+    emit_event("save")
 
 
-def _on_scene_open(*args):
-    avalon.api.emit("open", args)
+def _on_scene_open():
+    emit_event("open")
 
 
 def _before_scene_save(return_code, client_data):
@@ -166,7 +169,7 @@ def _before_scene_save(return_code, client_data):
     # in order to block the operation.
     OpenMaya.MScriptUtil.setBool(return_code, True)
 
-    avalon.api.emit("before_save", [return_code, client_data])
+    emit_event("before.save")
 
 
 def uninstall():
@@ -343,7 +346,7 @@ def containerise(name,
     return container
 
 
-def on_init(_):
+def on_init():
     log.info("Running callback on init..")
 
     def safe_deferred(fn):
@@ -384,12 +387,12 @@ def on_init(_):
         safe_deferred(override_toolbox_ui)
 
 
-def on_before_save(return_code, _):
+def on_before_save():
     """Run validation for scene's FPS prior to saving"""
     return lib.validate_fps()
 
 
-def on_save(_):
+def on_save():
     """Automatically add IDs to new nodes
 
     Any transform of a mesh, without an existing ID, is given one
@@ -407,7 +410,7 @@ def on_save(_):
         lib.set_id(node, new_id, overwrite=False)
 
 
-def on_open(_):
+def on_open():
     """On scene open let's assume the containers have changed."""
 
     from Qt import QtWidgets
@@ -455,7 +458,7 @@ def on_open(_):
             dialog.show()
 
 
-def on_new(_):
+def on_new():
     """Set project resolution and fps when create a new file"""
     log.info("Running callback on new..")
     with lib.suspended_refresh():
@@ -471,7 +474,7 @@ def on_new(_):
         lib.set_context_settings()
 
 
-def on_task_changed(*args):
+def on_task_changed():
     """Wrapped function of app initialize and maya's on task changed"""
     # Run
     menu.update_menu_task_label()
@@ -509,7 +512,7 @@ def on_task_changed(*args):
 
 
 def before_workfile_save(event):
-    workdir_path = event.workdir_path
+    workdir_path = event["workdir_path"]
     if workdir_path:
         copy_workspace_mel(workdir_path)
 
diff --git a/openpype/hosts/nuke/api/pipeline.py b/openpype/hosts/nuke/api/pipeline.py
index 8c6c9ca55b..1a5116c9ea 100644
--- a/openpype/hosts/nuke/api/pipeline.py
+++ b/openpype/hosts/nuke/api/pipeline.py
@@ -14,6 +14,7 @@ from openpype.api import (
     BuildWorkfile,
     get_current_project_settings
 )
+from openpype.pipeline import register_event_callback
 from openpype.tools.utils import host_tools
 
 from .command import viewer_update_and_undo_stop
@@ -102,8 +103,8 @@ def install():
     avalon.api.register_plugin_path(avalon.api.InventoryAction, INVENTORY_PATH)
 
     # Register Avalon event for workfiles loading.
-    avalon.api.on("workio.open_file", check_inventory_versions)
-    avalon.api.on("taskChanged", change_context_label)
+    register_event_callback("workio.open_file", check_inventory_versions)
+    register_event_callback("taskChanged", change_context_label)
 
     pyblish.api.register_callback(
         "instanceToggled", on_pyblish_instance_toggled)
@@ -226,7 +227,7 @@ def _uninstall_menu():
         menu.removeItem(item.name())
 
 
-def change_context_label(*args):
+def change_context_label():
     menubar = nuke.menu("Nuke")
     menu = menubar.findItem(MENU_LABEL)
 
diff --git a/openpype/hosts/photoshop/api/pipeline.py b/openpype/hosts/photoshop/api/pipeline.py
index 25983f2471..2aade59812 100644
--- a/openpype/hosts/photoshop/api/pipeline.py
+++ b/openpype/hosts/photoshop/api/pipeline.py
@@ -1,5 +1,4 @@
 import os
-import sys
 from Qt import QtWidgets
 
 import pyblish.api
@@ -7,6 +6,7 @@ import avalon.api
 from avalon import pipeline, io
 
 from openpype.api import Logger
+from openpype.pipeline import register_event_callback
 import openpype.hosts.photoshop
 
 from . import lib
@@ -75,7 +75,7 @@ def install():
         "instanceToggled", on_pyblish_instance_toggled
     )
 
-    avalon.api.on("application.launched", on_application_launch)
+    register_event_callback("application.launched", on_application_launch)
 
 
 def uninstall():
diff --git a/openpype/hosts/tvpaint/api/communication_server.py b/openpype/hosts/tvpaint/api/communication_server.py
index e9c5f4c73e..b001b84203 100644
--- a/openpype/hosts/tvpaint/api/communication_server.py
+++ b/openpype/hosts/tvpaint/api/communication_server.py
@@ -21,7 +21,7 @@ from aiohttp_json_rpc.protocol import (
 )
 from aiohttp_json_rpc.exceptions import RpcError
 
-from avalon import api
+from openpype.pipeline import emit_event
 from openpype.hosts.tvpaint.tvpaint_plugin import get_plugin_files_path
 
 log = logging.getLogger(__name__)
@@ -754,7 +754,7 @@ class BaseCommunicator:
 
         self._on_client_connect()
 
-        api.emit("application.launched")
+        emit_event("application.launched")
 
     def _on_client_connect(self):
         self._initial_textfile_write()
@@ -938,5 +938,5 @@ class QtCommunicator(BaseCommunicator):
 
     def _exit(self, *args, **kwargs):
         super()._exit(*args, **kwargs)
-        api.emit("application.exit")
+        emit_event("application.exit")
         self.qt_app.exit(self.exit_code)
diff --git a/openpype/hosts/tvpaint/api/pipeline.py b/openpype/hosts/tvpaint/api/pipeline.py
index 74eb41892c..b999478fb1 100644
--- a/openpype/hosts/tvpaint/api/pipeline.py
+++ b/openpype/hosts/tvpaint/api/pipeline.py
@@ -14,6 +14,7 @@ from avalon.pipeline import AVALON_CONTAINER_ID
 
 from openpype.hosts import tvpaint
 from openpype.api import get_current_project_settings
+from openpype.pipeline import register_event_callback
 
 from .lib import (
     execute_george,
@@ -84,8 +85,8 @@ def install():
     if on_instance_toggle not in registered_callbacks:
         pyblish.api.register_callback("instanceToggled", on_instance_toggle)
 
-    avalon.api.on("application.launched", initial_launch)
-    avalon.api.on("application.exit", application_exit)
+    register_event_callback("application.launched", initial_launch)
+    register_event_callback("application.exit", application_exit)
 
 
 def uninstall():
diff --git a/openpype/hosts/webpublisher/api/__init__.py b/openpype/hosts/webpublisher/api/__init__.py
index e40d46d662..f338c92a5e 100644
--- a/openpype/hosts/webpublisher/api/__init__.py
+++ b/openpype/hosts/webpublisher/api/__init__.py
@@ -16,10 +16,6 @@ LOAD_PATH = os.path.join(PLUGINS_DIR, "load")
 CREATE_PATH = os.path.join(PLUGINS_DIR, "create")
 
 
-def application_launch():
-    pass
-
-
 def install():
     print("Installing Pype config...")
 
@@ -29,7 +25,6 @@ def install():
     log.info(PUBLISH_PATH)
 
     io.install()
-    avalon.on("application.launched", application_launch)
 
 
 def uninstall():
diff --git a/openpype/tools/loader/app.py b/openpype/tools/loader/app.py
index aa743b05fe..afb94bf8fc 100644
--- a/openpype/tools/loader/app.py
+++ b/openpype/tools/loader/app.py
@@ -1,9 +1,10 @@
 import sys
 
 from Qt import QtWidgets, QtCore
-from avalon import api, io, pipeline
+from avalon import api, io
 
 from openpype import style
+from openpype.pipeline import register_event_callback
 from openpype.tools.utils import (
     lib,
     PlaceholderLineEdit
@@ -33,7 +34,7 @@ def on_context_task_change(*args, **kwargs):
         module.window.on_context_task_change(*args, **kwargs)
 
 
-pipeline.on("taskChanged", on_context_task_change)
+register_event_callback("taskChanged", on_context_task_change)
 
 
 class LoaderWindow(QtWidgets.QDialog):
diff --git a/openpype/tools/workfiles/app.py b/openpype/tools/workfiles/app.py
index aece7bfb4f..280fe2d8a2 100644
--- a/openpype/tools/workfiles/app.py
+++ b/openpype/tools/workfiles/app.py
@@ -9,10 +9,10 @@ import datetime
 
 import Qt
 from Qt import QtWidgets, QtCore
-from avalon import io, api, pipeline
+from avalon import io, api
 
 from openpype import style
-from openpype.pipeline.lib import BeforeWorkfileSave
+from openpype.pipeline import emit_event
 from openpype.tools.utils.lib import (
     qt_app_context
 )
@@ -823,7 +823,11 @@ class FilesWidget(QtWidgets.QWidget):
             return
 
         # Trigger before save event
-        BeforeWorkfileSave.emit(work_filename, self._workdir_path)
+        emit_event(
+            "before.workfile.save",
+            {"filename": work_filename, "workdir_path": self._workdir_path},
+            source="workfiles.tool"
+        )
 
         # Make sure workfiles root is updated
         # - this triggers 'workio.work_root(...)' which may change value of
@@ -853,7 +857,11 @@ class FilesWidget(QtWidgets.QWidget):
             api.Session["AVALON_PROJECT"]
         )
         # Trigger after save events
-        pipeline.emit("after.workfile.save", [filepath])
+        emit_event(
+            "after.workfile.save",
+            {"filepath": filepath},
+            source="workfiles.tool"
+        )
 
         self.workfile_created.emit(filepath)
         # Refresh files model