diff --git a/compose/production/django/Dockerfile b/compose/production/django/Dockerfile
index 87abf65..f14b81e 100644
--- a/compose/production/django/Dockerfile
+++ b/compose/production/django/Dockerfile
@@ -1,5 +1,5 @@
 
-FROM python:3.8-slim-buster
+FROM python:3.8-slim
 
 ENV PYTHONUNBUFFERED 1
 
diff --git a/config/settings/base.py b/config/settings/base.py
index d29cb09..aa891a4 100644
--- a/config/settings/base.py
+++ b/config/settings/base.py
@@ -287,3 +287,4 @@
 CORS_URLS_REGEX = r"^/api/.*$"
 # Your stuff...
 # ------------------------------------------------------------------------------
+VALIDATE_SPEC = env.bool("VALIDATE_SPEC", True)
diff --git a/openapi_documentor/conftest.py b/openapi_documentor/conftest.py
index 2e88c50..be85299 100644
--- a/openapi_documentor/conftest.py
+++ b/openapi_documentor/conftest.py
@@ -1,7 +1,13 @@
 import pytest
-
+from django.conf import settings
 from openapi_documentor.users.models import User
 from openapi_documentor.users.tests.factories import UserFactory
+from openapi_documentor.openapi.tests.factories import DocumentFactory
+
+
+open_api_file = settings.APPS_DIR / "openapi/tests/fixtures/hello.yaml"
+with open(open_api_file) as fout:
+    open_api_doc = fout.read()
 
 
 @pytest.fixture(autouse=True)
@@ -12,3 +18,13 @@ def media_storage(settings, tmpdir):
 @pytest.fixture
 def user() -> User:
     return UserFactory()
+
+
+@pytest.fixture
+def document(openapi) -> User:
+    return DocumentFactory(doc=openapi)
+
+
+@pytest.fixture
+def openapi() -> str:
+    return open_api_doc
diff --git a/openapi_documentor/openapi/admin.py b/openapi_documentor/openapi/admin.py
index 76684e1..0b79e24 100644
--- a/openapi_documentor/openapi/admin.py
+++ b/openapi_documentor/openapi/admin.py
@@ -1,4 +1,7 @@
 from django.contrib import admin
+from django.db.models import Q
+from django.http.request import HttpRequest
+from django.http.response import HttpResponse
 
 # Register your models here.
 # from guardian.admin import GuardedModelAdmin
@@ -19,4 +22,15 @@ def get_queryset(self, request):
         qs = super(DocumentAdmin, self).get_queryset(request)
         if request.user.is_superuser:
             return qs
-        return qs.filter(owner=request.user)
+        return qs.filter(Q(owner=request.user) | Q(editors=request.user)).distinct()
+
+    def change_view(
+        self, request: HttpRequest, object_id: str, **kwargs
+    ) -> HttpResponse:
+        if not (
+            request.user.is_superuser
+            or request.user.document_set.filter(pk=object_id).exists()
+        ):
+            self.exclude = ["editors"]
+            self.readonly_fields = ["owner"]
+        return super().change_view(request, object_id, **kwargs)
diff --git a/openapi_documentor/openapi/migrations/0007_auto_20230630_1414.py b/openapi_documentor/openapi/migrations/0007_auto_20230630_1414.py
new file mode 100644
index 0000000..fbe4d55
--- /dev/null
+++ b/openapi_documentor/openapi/migrations/0007_auto_20230630_1414.py
@@ -0,0 +1,30 @@
+# Generated by Django 3.1.7 on 2023-06-30 14:14
+
+from django.conf import settings
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        migrations.swappable_dependency(settings.AUTH_USER_MODEL),
+        ('openapi', '0006_auto_20210321_1802'),
+    ]
+
+    operations = [
+        migrations.AddField(
+            model_name='document',
+            name='editors',
+            field=models.ManyToManyField(blank=True, default=None, related_name='editors', to=settings.AUTH_USER_MODEL),
+        ),
+        migrations.AlterField(
+            model_name='document',
+            name='created',
+            field=models.DateTimeField(auto_now_add=True, verbose_name='date published'),
+        ),
+        migrations.AlterField(
+            model_name='document',
+            name='modified',
+            field=models.DateTimeField(auto_now=True, verbose_name='date modified'),
+        ),
+    ]
diff --git a/openapi_documentor/openapi/models.py b/openapi_documentor/openapi/models.py
index afee421..0d070b9 100644
--- a/openapi_documentor/openapi/models.py
+++ b/openapi_documentor/openapi/models.py
@@ -4,13 +4,14 @@
 import yaml
 
 try:
-    from yaml import CLoader as YamlLoader
+    from yaml import Loader as YamlLoader
 except ImportError:
     from yaml import YamlLoader
 
 from django.core.exceptions import ValidationError
 from django.db import models
 from django.urls import reverse
+from django.conf import settings
 from django.utils.translation import gettext_lazy as _
 from openapi_spec_validator import validate_spec
 from taggit.managers import TaggableManager
@@ -45,8 +46,9 @@ class Document(models.Model):
         default=OpenapiVersions.THREEZERO,
     )  # oas 3.0
     owner = models.ForeignKey(User, on_delete=models.DO_NOTHING, default=None)
-    created = models.DateTimeField("date published")
-    modified = models.DateTimeField("date modified")
+    created = models.DateTimeField("date published", auto_now_add=True)
+    modified = models.DateTimeField("date modified", auto_now=True)
+    editors = models.ManyToManyField(User, default=None, related_name="editors", blank=True)
     tags = TaggableManager(through=TaggedDocument)
 
     class Meta:
@@ -56,6 +58,8 @@ def clean(self):
         parsed_doc = self._parse_doc(self.doc)
         if not parsed_doc:
             raise ValidationError(_("Only Json and Yaml are allowed"))
+        if not settings.VALIDATE_SPEC:
+            return
         try:
             validate_spec(parsed_doc)
         except:  # noqa: E722
@@ -64,7 +68,7 @@ def clean(self):
     def save(self, *args, **kwargs):
         parsed_doc = self._parse_doc(self.doc)
         if parsed_doc:
-            self.formatted = json.dumps(parsed_doc)
+            self.formatted = json.dumps(parsed_doc, default=str)
         super().save(*args, **kwargs)
 
     def get_absolute_url(self):
diff --git a/openapi_documentor/openapi/tests/factories.py b/openapi_documentor/openapi/tests/factories.py
new file mode 100644
index 0000000..ac1f964
--- /dev/null
+++ b/openapi_documentor/openapi/tests/factories.py
@@ -0,0 +1,10 @@
+from factory import Faker
+from factory.django import DjangoModelFactory
+from openapi_documentor.openapi.models import Document
+
+
+class DocumentFactory(DjangoModelFactory):
+    title = Faker("user_name")
+
+    class Meta:
+        model = Document
diff --git a/openapi_documentor/openapi/tests/fixtures/hello.yaml b/openapi_documentor/openapi/tests/fixtures/hello.yaml
new file mode 100644
index 0000000..7da2aed
--- /dev/null
+++ b/openapi_documentor/openapi/tests/fixtures/hello.yaml
@@ -0,0 +1,15 @@
+openapi: 3.0.0
+info:
+  title: Minimal API
+  version: 1.0.0
+paths:
+  /hello:
+    get:
+      summary: Retrieve a greeting message
+      responses:
+        "200":
+          description: Successful response
+          content:
+            text/plain:
+              schema:
+                type: string
diff --git a/openapi_documentor/openapi/tests/test_admin.py b/openapi_documentor/openapi/tests/test_admin.py
new file mode 100644
index 0000000..dfea5f5
--- /dev/null
+++ b/openapi_documentor/openapi/tests/test_admin.py
@@ -0,0 +1,52 @@
+from unittest.mock import Mock
+
+import pytest
+from django.urls import reverse
+from django.contrib.admin.sites import AdminSite
+
+from openapi_documentor.openapi.models import Document
+from openapi_documentor.openapi.admin import DocumentAdmin
+from openapi_documentor.openapi.tests.factories import DocumentFactory
+from openapi_documentor.users.tests.factories import UserFactory
+
+pytestmark = pytest.mark.django_db
+
+
+class TestDocumentAdmin:
+    def test_add(self, admin_client, user, openapi):
+        url = reverse("admin:openapi_document_add")
+        response = admin_client.get(url)
+        assert response.status_code == 200
+
+        response = admin_client.post(
+            url,
+            data={
+                "title": "MyApiDoc",
+                "doc": openapi,
+                "owner": user.pk,
+                "version": "3.0.0",
+                "rev": "1.0.0",
+                "tags": ["test"],
+            },
+        )
+        assert response.status_code == 302
+        assert Document.objects.filter(title="MyApiDoc", owner=user).exists()
+
+    def test_list_docs_with_editor_access(self):
+        user1 = UserFactory()
+        user2 = UserFactory()
+        u1_private_doc = DocumentFactory.create_batch(3, owner=user1)
+        u1_shared = DocumentFactory.create_batch(2, owner=user1)
+        # user1 shared editor access with user2
+        for d in u1_shared:
+            d.editors.add(user2)
+
+        u2_private_doc = DocumentFactory.create_batch(2, owner=user2)
+
+        doc_admin = DocumentAdmin(model=Document, admin_site=AdminSite())
+        qs1 = doc_admin.get_queryset(request=Mock(user=user1))
+
+        assert qs1.count() == len(u1_private_doc + u1_shared)
+
+        qs2 = doc_admin.get_queryset(request=Mock(user=user2))
+        assert qs2.count() == len(u2_private_doc + u1_shared)
diff --git a/openapi_documentor/templates/openapi/document_detail.html b/openapi_documentor/templates/openapi/document_detail.html
index 50896d8..1833827 100644
--- a/openapi_documentor/templates/openapi/document_detail.html
+++ b/openapi_documentor/templates/openapi/document_detail.html
@@ -1,7 +1,7 @@
 {% extends "base.html" %}
 {% load static %}
 {% block custom_javascript %}
-  <script defer src="https://cdn.jsdelivr.net/npm/redoc@next/bundles/redoc.standalone.js"></script>
+  <script defer src="https://cdn.jsdelivr.net/npm/redoc@2.1.0/bundles/redoc.standalone.js"></script>
 {% endblock custom_javascript %}
 
 {% block title %}Api: {{ object.title }}{% endblock %}
diff --git a/requirements/local.txt b/requirements/local.txt
index c898704..df106a6 100644
--- a/requirements/local.txt
+++ b/requirements/local.txt
@@ -5,7 +5,7 @@ ipdb==0.13.5  # https://github.com/gotcha/ipdb
 
 # Testing
 # ------------------------------------------------------------------------------
-mypy==0.812  # https://github.com/python/mypy
+mypy==1.5.1  # https://github.com/python/mypy
 django-stubs==1.7.0  # https://github.com/typeddjango/django-stubs
 pytest==6.2.2  # https://github.com/pytest-dev/pytest
 pytest-sugar==0.9.4  # https://github.com/Frozenball/pytest-sugar
@@ -32,3 +32,4 @@ django-debug-toolbar==3.2  # https://github.com/jazzband/django-debug-toolbar
 django-extensions==3.1.1  # https://github.com/django-extensions/django-extensions
 django-coverage-plugin==1.8.0  # https://github.com/nedbat/django_coverage_plugin
 pytest-django==4.1.0  # https://github.com/pytest-dev/pytest-django
+typed-ast==1.5.4