diff --git a/gns3server/compute/iou/__init__.py b/gns3server/compute/iou/__init__.py
index 028736b7..89d47e3e 100644
--- a/gns3server/compute/iou/__init__.py
+++ b/gns3server/compute/iou/__init__.py
@@ -25,7 +25,6 @@ import asyncio
 from ..base_manager import BaseManager
 from .iou_error import IOUError
 from .iou_vm import IOUVM
-from .utils.application_id import get_next_application_id
 
 import logging
 log = logging.getLogger(__name__)
@@ -48,12 +47,7 @@ class IOU(BaseManager):
         :returns: IOUVM instance
         """
 
-        async with self._iou_id_lock:
-            # wait for a node to be completely created before adding a new one
-            # this is important otherwise we allocate the same application ID
-            # when creating multiple IOU node at the same time
-            application_id = get_next_application_id(self.nodes)
-            node = await super().create_node(*args, application_id=application_id, **kwargs)
+        node = await super().create_node(*args, **kwargs)
         return node
 
     @staticmethod
diff --git a/gns3server/compute/iou/iou_vm.py b/gns3server/compute/iou/iou_vm.py
index 9db7c88d..e08357ef 100644
--- a/gns3server/compute/iou/iou_vm.py
+++ b/gns3server/compute/iou/iou_vm.py
@@ -70,6 +70,10 @@ class IOUVM(BaseNode):
 
         super().__init__(name, node_id, project, manager, console=console, console_type=console_type)
 
+        log.info('IOU "{name}" [{id}]: assigned with application ID {application_id}'.format(name=self._name,
+                                                                                             id=self._id,
+                                                                                             application_id=application_id))
+
         self._iou_process = None
         self._telnet_server = None
         self._iou_stdout_file = ""
diff --git a/gns3server/controller/__init__.py b/gns3server/controller/__init__.py
index cae729d4..20132f81 100644
--- a/gns3server/controller/__init__.py
+++ b/gns3server/controller/__init__.py
@@ -481,7 +481,7 @@ class Controller:
     @property
     def projects(self):
         """
-        :returns: The dictionary of projects managed by GNS3
+        :returns: The dictionary of projects managed by the controller
         """
 
         return self._projects
diff --git a/gns3server/controller/project.py b/gns3server/controller/project.py
index 29f9e405..04d4a798 100644
--- a/gns3server/controller/project.py
+++ b/gns3server/controller/project.py
@@ -38,6 +38,7 @@ from .topology import project_to_topology, load_topology
 from .udp_link import UDPLink
 from ..config import Config
 from ..utils.path import check_path_allowed, get_default_project_directory
+from ..utils.application_id import get_next_application_id
 from ..utils.asyncio.pool import Pool
 from ..utils.asyncio import locking
 from ..utils.asyncio import aiozipstream
@@ -126,6 +127,8 @@ class Project:
             assert self._status != "closed"
             self.dump()
 
+        self._iou_id_lock = asyncio.Lock()
+
     def emit_notification(self, action, event):
         """
         Emit a notification to all clients using this project.
@@ -516,17 +519,7 @@ class Project:
         node = await self.add_node(compute, name, node_id, node_type=node_type, **template)
         return node
 
-    @open_required
-    async def add_node(self, compute, name, node_id, dump=True, node_type=None, **kwargs):
-        """
-        Create a node or return an existing node
-
-        :param dump: Dump topology to disk
-        :param kwargs: See the documentation of node
-        """
-
-        if node_id in self._nodes:
-            return self._nodes[node_id]
+    async def _create_node(self, compute, name, node_id, node_type=None, **kwargs):
 
         node = Node(self, compute, name, node_id=node_id, node_type=node_type, **kwargs)
         if compute not in self._project_created_on_compute:
@@ -547,10 +540,39 @@ class Project:
                 data["variables"] = self._variables
 
             await compute.post("/projects", data=data)
-
             self._project_created_on_compute.add(compute)
+
         await node.create()
         self._nodes[node.id] = node
+
+        return node
+
+    @open_required
+    async def add_node(self, compute, name, node_id, dump=True, node_type=None, **kwargs):
+        """
+        Create a node or return an existing node
+
+        :param dump: Dump topology to disk
+        :param kwargs: See the documentation of node
+        """
+
+        if node_id in self._nodes:
+            return self._nodes[node_id]
+
+        if node_type == "iou":
+            async with self._iou_id_lock:
+                # wait for a IOU node to be completely created before adding a new one
+                # this is important otherwise we allocate the same application ID (used
+                # to generate MAC addresses) when creating multiple IOU node at the same time
+                if "properties" in kwargs.keys():
+                    # allocate a new application id for nodes loaded from the project
+                    kwargs.get("properties")["application_id"] = get_next_application_id(self._controller.projects, compute)
+                elif "application_id" not in kwargs.keys() and not kwargs.get("properties"):
+                    # allocate a new application id for nodes added to the project
+                    kwargs["application_id"] = get_next_application_id(self._controller.projects, compute)
+                node = await self._create_node(compute, name, node_id, node_type, **kwargs)
+        else:
+            node = await self._create_node(compute, name, node_id, node_type, **kwargs)
         self.emit_notification("node.created", node.__json__())
         if dump:
             self.dump()
@@ -1102,12 +1124,11 @@ class Project:
         data['z'] = z
         data['locked'] = False  # duplicated node must not be locked
         new_node_uuid = str(uuid.uuid4())
-        new_node = await self.add_node(
-            node.compute,
-            node.name,
-            new_node_uuid,
-            node_type=node_type,
-            **data)
+        new_node = await self.add_node(node.compute,
+                                       node.name,
+                                       new_node_uuid,
+                                       node_type=node_type,
+                                       **data)
         try:
             await node.post("/duplicate", timeout=None, data={
                 "destination_node_id": new_node_uuid
diff --git a/gns3server/handlers/api/compute/iou_handler.py b/gns3server/handlers/api/compute/iou_handler.py
index 43b1c07f..5238f90c 100644
--- a/gns3server/handlers/api/compute/iou_handler.py
+++ b/gns3server/handlers/api/compute/iou_handler.py
@@ -58,16 +58,17 @@ class IOUHandler:
 
         iou = IOU.instance()
         vm = await iou.create_node(request.json.pop("name"),
-                                        request.match_info["project_id"],
-                                        request.json.get("node_id"),
-                                        path=request.json.get("path"),
-                                        console=request.json.get("console"),
-                                        console_type=request.json.get("console_type", "telnet"))
+                                   request.match_info["project_id"],
+                                   request.json.get("node_id"),
+                                   application_id=request.json.get("application_id"),
+                                   path=request.json.get("path"),
+                                   console=request.json.get("console"),
+                                   console_type=request.json.get("console_type", "telnet"))
 
         for name, value in request.json.items():
             if hasattr(vm, name) and getattr(vm, name) != value:
                 if name == "application_id":
-                    continue  # we must ignore this to avoid overwriting the application_id allocated by the IOU manager
+                    continue  # we must ignore this to avoid overwriting the application_id allocated by the controller
                 if name == "startup_config_content" and (vm.startup_config_content and len(vm.startup_config_content) > 0):
                     continue
                 if name == "private_config_content" and (vm.private_config_content and len(vm.private_config_content) > 0):
diff --git a/gns3server/schemas/iou.py b/gns3server/schemas/iou.py
index 84aa5421..a10c96f8 100644
--- a/gns3server/schemas/iou.py
+++ b/gns3server/schemas/iou.py
@@ -96,7 +96,7 @@ IOU_CREATE_SCHEMA = {
         },
     },
     "additionalProperties": False,
-    "required": ["name", "path"]
+    "required": ["application_id", "name", "path"]
 }
 
 
diff --git a/gns3server/compute/iou/utils/application_id.py b/gns3server/utils/application_id.py
similarity index 56%
rename from gns3server/compute/iou/utils/application_id.py
rename to gns3server/utils/application_id.py
index 1caf9b3b..95fc76ad 100644
--- a/gns3server/compute/iou/utils/application_id.py
+++ b/gns3server/utils/application_id.py
@@ -15,24 +15,32 @@
 # You should have received a copy of the GNU General Public License
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
-from ..iou_error import IOUError
+import aiohttp
 
 import logging
 log = logging.getLogger(__name__)
 
 
-def get_next_application_id(nodes):
+def get_next_application_id(projects, compute):
     """
     Calculates free application_id from given nodes
 
-    :param nodes:
-    :raises IOUError when exceeds number
+    :param projects: all projects managed by controller
+    :param compute: Compute instance
+    :raises HTTPConflict when exceeds number
     :return: integer first free id
     """
 
-    used = set([n.application_id for n in nodes])
+    nodes = []
+
+    # look for application id for in all nodes across all opened projects that share the same compute
+    for project in projects.values():
+        if project.status == "opened" and compute in project.computes:
+            nodes.extend(list(project.nodes.values()))
+
+    used = set([n.properties["application_id"] for n in nodes if n.node_type == "iou"])
     pool = set(range(1, 512))
     try:
         return (pool - used).pop()
     except KeyError:
-        raise IOUError("Cannot create a new IOU VM (limit of 512 VMs on one host reached)")
+        raise aiohttp.web.HTTPConflict(text="Cannot create a new IOU node (limit of 512 nodes across all opened projects using compute {} reached".format(compute.name))
diff --git a/tests/compute/iou/test_iou_manager.py b/tests/compute/iou/test_iou_manager.py
deleted file mode 100644
index 4a3475ea..00000000
--- a/tests/compute/iou/test_iou_manager.py
+++ /dev/null
@@ -1,79 +0,0 @@
-# -*- coding: utf-8 -*-
-#
-# Copyright (C) 2015 GNS3 Technologies Inc.
-#
-# This program is free software: you can redistribute it and/or modify
-# it under the terms of the GNU General Public License as published by
-# the Free Software Foundation, either version 3 of the License, or
-# (at your option) any later version.
-#
-# This program is distributed in the hope that it will be useful,
-# but WITHOUT ANY WARRANTY; without even the implied warranty of
-# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-# GNU General Public License for more details.
-#
-# You should have received a copy of the GNU General Public License
-# along with this program.  If not, see <http://www.gnu.org/licenses/>.
-
-
-import pytest
-from unittest.mock import patch
-import uuid
-import sys
-
-pytestmark = pytest.mark.skipif(sys.platform.startswith("win"), reason="Not supported on Windows")
-
-if not sys.platform.startswith("win"):
-    from gns3server.compute.iou import IOU
-    from gns3server.compute.iou.iou_error import IOUError
-
-from gns3server.compute.project_manager import ProjectManager
-
-
-@pytest.fixture(scope="function")
-def iou(port_manager):
-    # Cleanup the IOU object
-    IOU._instance = None
-    iou = IOU.instance()
-    iou.port_manager = port_manager
-    return iou
-
-
-def test_application_id(loop, project, iou):
-    vm1_id = str(uuid.uuid4())
-    vm2_id = str(uuid.uuid4())
-    vm3_id = str(uuid.uuid4())
-    vm1 = loop.run_until_complete(iou.create_node("PC 1", project.id, vm1_id))
-    vm2 = loop.run_until_complete(iou.create_node("PC 2", project.id, vm2_id))
-    assert vm1.application_id == 1
-    assert vm2.application_id == 2
-    loop.run_until_complete(iou.delete_node(vm1_id))
-    vm3 = loop.run_until_complete(iou.create_node("PC 3", project.id, vm3_id))
-    assert vm3.application_id == 1
-
-
-def test_get_application_id_multiple_project(loop, iou):
-    vm1_id = str(uuid.uuid4())
-    vm2_id = str(uuid.uuid4())
-    vm3_id = str(uuid.uuid4())
-    project1 = ProjectManager.instance().create_project(project_id=str(uuid.uuid4()))
-    project2 = ProjectManager.instance().create_project(project_id=str(uuid.uuid4()))
-    vm1 = loop.run_until_complete(iou.create_node("PC 1", project1.id, vm1_id))
-    vm2 = loop.run_until_complete(iou.create_node("PC 2", project1.id, vm2_id))
-    vm3 = loop.run_until_complete(iou.create_node("PC 2", project2.id, vm3_id))
-    assert vm1.application_id == 1
-    assert vm2.application_id == 2
-    assert vm3.application_id == 3
-
-
-def test_get_application_id_no_id_available(loop, project, iou):
-    with pytest.raises(IOUError):
-        for i in range(1, 513):
-            node_id = str(uuid.uuid4())
-            vm = loop.run_until_complete(iou.create_node("PC {}".format(i), project.id, node_id))
-            assert vm.application_id == i
-
-
-def test_get_images_directory(iou, tmpdir):
-    with patch("gns3server.config.Config.get_section_config", return_value={"images_path": str(tmpdir)}):
-        assert iou.get_images_directory() == str(tmpdir / "IOU")
diff --git a/tests/controller/test_project.py b/tests/controller/test_project.py
index 4daca8a3..57d26a95 100644
--- a/tests/controller/test_project.py
+++ b/tests/controller/test_project.py
@@ -28,6 +28,7 @@ from uuid import uuid4
 
 from gns3server.controller.project import Project
 from gns3server.controller.template import Template
+from gns3server.controller.node import Node
 from gns3server.controller.ports.ethernet_port import EthernetPort
 from gns3server.config import Config
 
@@ -204,6 +205,131 @@ def test_add_node_non_local(async_run, controller):
     project.emit_notification.assert_any_call("node.created", node.__json__())
 
 
+def test_add_node_iou(async_run, controller):
+    """
+    Test if an application ID is allocated for IOU nodes
+    """
+    compute = MagicMock()
+    compute.id = "local"
+    project = async_run(controller.add_project(project_id=str(uuid.uuid4()), name="test1"))
+    project.emit_notification = MagicMock()
+
+    response = MagicMock()
+    compute.post = AsyncioMagicMock(return_value=response)
+
+    node1 = async_run(project.add_node(compute, "test1", None, node_type="iou"))
+    node2 = async_run(project.add_node(compute, "test2", None, node_type="iou"))
+    node3 = async_run(project.add_node(compute, "test3", None, node_type="iou"))
+    assert node1.properties["application_id"] == 1
+    assert node2.properties["application_id"] == 2
+    assert node3.properties["application_id"] == 3
+
+
+def test_add_node_iou_with_multiple_projects(async_run, controller):
+    """
+    Test if an application ID is allocated for IOU nodes with different projects already opened
+    """
+    compute = MagicMock()
+    compute.id = "local"
+    project1 = async_run(controller.add_project(project_id=str(uuid.uuid4()), name="test1"))
+    project1.emit_notification = MagicMock()
+    project2 = async_run(controller.add_project(project_id=str(uuid.uuid4()), name="test2"))
+    project2.emit_notification = MagicMock()
+    project3 = async_run(controller.add_project(project_id=str(uuid.uuid4()), name="test3"))
+    project3.emit_notification = MagicMock()
+    response = MagicMock()
+    compute.post = AsyncioMagicMock(return_value=response)
+
+    node1 = async_run(project1.add_node(compute, "test1", None, node_type="iou"))
+    node2 = async_run(project1.add_node(compute, "test2", None, node_type="iou"))
+    node3 = async_run(project1.add_node(compute, "test3", None, node_type="iou"))
+
+    node4 = async_run(project2.add_node(compute, "test4", None, node_type="iou"))
+    node5 = async_run(project2.add_node(compute, "test5", None, node_type="iou"))
+    node6 = async_run(project2.add_node(compute, "test6", None, node_type="iou"))
+
+    node7 = async_run(project3.add_node(compute, "test7", None, node_type="iou"))
+    node8 = async_run(project3.add_node(compute, "test8", None, node_type="iou"))
+    node9 = async_run(project3.add_node(compute, "test9", None, node_type="iou"))
+
+    assert node1.properties["application_id"] == 1
+    assert node2.properties["application_id"] == 2
+    assert node3.properties["application_id"] == 3
+
+    assert node4.properties["application_id"] == 4
+    assert node5.properties["application_id"] == 5
+    assert node6.properties["application_id"] == 6
+
+    assert node7.properties["application_id"] == 7
+    assert node8.properties["application_id"] == 8
+    assert node9.properties["application_id"] == 9
+
+    controller.remove_project(project1)
+    project4 = async_run(controller.add_project(project_id=str(uuid.uuid4()), name="test4"))
+    project4.emit_notification = MagicMock()
+
+    node10 = async_run(project3.add_node(compute, "test10", None, node_type="iou"))
+    node11 = async_run(project3.add_node(compute, "test11", None, node_type="iou"))
+    node12 = async_run(project3.add_node(compute, "test12", None, node_type="iou"))
+
+    assert node10.properties["application_id"] == 1
+    assert node11.properties["application_id"] == 2
+    assert node12.properties["application_id"] == 3
+
+
+def test_add_node_iou_with_multiple_projects_different_computes(async_run, controller):
+    """
+    Test if an application ID is allocated for IOU nodes with different projects already opened
+    """
+    compute1 = MagicMock()
+    compute1.id = "remote1"
+    compute2 = MagicMock()
+    compute2.id = "remote2"
+    project1 = async_run(controller.add_project(project_id=str(uuid.uuid4()), name="test1"))
+    project1.emit_notification = MagicMock()
+    project2 = async_run(controller.add_project(project_id=str(uuid.uuid4()), name="test2"))
+    project2.emit_notification = MagicMock()
+    response = MagicMock()
+    compute1.post = AsyncioMagicMock(return_value=response)
+    compute2.post = AsyncioMagicMock(return_value=response)
+
+    node1 = async_run(project1.add_node(compute1, "test1", None, node_type="iou"))
+    node2 = async_run(project1.add_node(compute1, "test2", None, node_type="iou"))
+
+    node3 = async_run(project2.add_node(compute2, "test3", None, node_type="iou"))
+    node4 = async_run(project2.add_node(compute2, "test4", None, node_type="iou"))
+
+    assert node1.properties["application_id"] == 1
+    assert node2.properties["application_id"] == 2
+
+    assert node3.properties["application_id"] == 1
+    assert node4.properties["application_id"] == 2
+
+    node5 = async_run(project1.add_node(compute2, "test5", None, node_type="iou"))
+    node6 = async_run(project2.add_node(compute1, "test6", None, node_type="iou"))
+
+    assert node5.properties["application_id"] == 3
+    assert node6.properties["application_id"] == 4
+
+
+def test_add_node_iou_no_id_available(async_run, controller):
+    """
+    Test if an application ID is allocated for IOU nodes
+    """
+    compute = MagicMock()
+    compute.id = "local"
+    project = async_run(controller.add_project(project_id=str(uuid.uuid4()), name="test"))
+    project.emit_notification = MagicMock()
+    response = MagicMock()
+    compute.post = AsyncioMagicMock(return_value=response)
+
+    with pytest.raises(aiohttp.web.HTTPConflict):
+        for i in range(1, 513):
+            prop = {"properties": {"application_id": i}}
+            project._nodes[i] = Node(project, compute, "Node{}".format(i), node_id=i, node_type="iou", **prop)
+        async_run(project.add_node(compute, "test1", None, node_type="iou"))
+
+
 def test_add_node_from_template(async_run, controller):
     """
     For a local server we send the project path
diff --git a/tests/handlers/api/compute/test_iou.py b/tests/handlers/api/compute/test_iou.py
index 9058a9d7..180b2043 100644
--- a/tests/handlers/api/compute/test_iou.py
+++ b/tests/handlers/api/compute/test_iou.py
@@ -42,7 +42,7 @@ def fake_iou_bin(images_dir):
 @pytest.fixture
 def base_params(tmpdir, fake_iou_bin):
     """Return standard parameters"""
-    return {"name": "PC TEST 1", "path": "iou.bin"}
+    return {"application_id": 42, "name": "PC TEST 1", "path": "iou.bin"}
 
 
 @pytest.fixture