diff --git a/.github/PULL_REQUEST_TEMPLATE.md b/.github/PULL_REQUEST_TEMPLATE.md
index b8add87..9d6c6e2 100644
--- a/.github/PULL_REQUEST_TEMPLATE.md
+++ b/.github/PULL_REQUEST_TEMPLATE.md
@@ -2,5 +2,5 @@
 
 I have completed the following tasks
 
-- [ ] Basic endpoints
-- [ ] Collaborator feature
+- [x] Basic endpoints
+- [x] Collaborator feature
diff --git a/Pipfile b/Pipfile
index a6563bd..3e49bbb 100644
--- a/Pipfile
+++ b/Pipfile
@@ -14,4 +14,4 @@ gunicorn = "*"
 drf-yasg = "*"
 
 [requires]
-python_version = "3.8"
+python_version = "3.6"
diff --git a/Pipfile.lock b/Pipfile.lock
index f5965b1..15227a3 100644
--- a/Pipfile.lock
+++ b/Pipfile.lock
@@ -1,11 +1,11 @@
 {
     "_meta": {
         "hash": {
-            "sha256": "90a78ef190530d701fb120f1af60525e7c1eeab94face596902fdd03cc19a9db"
+            "sha256": "51fcca81c5defd78ec8a5dc6b087c0bb6f9ae6d911a5135ba638a670d8577393"
         },
         "pipfile-spec": 6,
         "requires": {
-            "python_version": "3.8"
+            "python_version": "3.6"
         },
         "sources": [
             {
diff --git a/api/migrations/0003_todo_collaborators.py b/api/migrations/0003_todo_collaborators.py
new file mode 100644
index 0000000..53c3493
--- /dev/null
+++ b/api/migrations/0003_todo_collaborators.py
@@ -0,0 +1,20 @@
+# Generated by Django 3.0.6 on 2020-05-12 14:37
+
+from django.conf import settings
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        migrations.swappable_dependency(settings.AUTH_USER_MODEL),
+        ('api', '0002_todo_creator'),
+    ]
+
+    operations = [
+        migrations.AddField(
+            model_name='todo',
+            name='collaborators',
+            field=models.ManyToManyField(related_name='collaborators', to=settings.AUTH_USER_MODEL),
+        ),
+    ]
diff --git a/api/migrations/0004_auto_20200512_2008.py b/api/migrations/0004_auto_20200512_2008.py
new file mode 100644
index 0000000..71c10af
--- /dev/null
+++ b/api/migrations/0004_auto_20200512_2008.py
@@ -0,0 +1,20 @@
+# Generated by Django 3.0.6 on 2020-05-12 14:38
+
+from django.conf import settings
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        migrations.swappable_dependency(settings.AUTH_USER_MODEL),
+        ('api', '0003_todo_collaborators'),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name='todo',
+            name='collaborators',
+            field=models.ManyToManyField(null=True, related_name='collaborators', to=settings.AUTH_USER_MODEL),
+        ),
+    ]
diff --git a/api/migrations/0005_auto_20200512_2010.py b/api/migrations/0005_auto_20200512_2010.py
new file mode 100644
index 0000000..fc5030d
--- /dev/null
+++ b/api/migrations/0005_auto_20200512_2010.py
@@ -0,0 +1,20 @@
+# Generated by Django 3.0.6 on 2020-05-12 14:40
+
+from django.conf import settings
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        migrations.swappable_dependency(settings.AUTH_USER_MODEL),
+        ('api', '0004_auto_20200512_2008'),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name='todo',
+            name='collaborators',
+            field=models.ManyToManyField(related_name='collaborators', to=settings.AUTH_USER_MODEL),
+        ),
+    ]
diff --git a/api/models.py b/api/models.py
index ab3ca0a..4807f5d 100644
--- a/api/models.py
+++ b/api/models.py
@@ -5,6 +5,6 @@
 class Todo(models.Model):
     creator = models.ForeignKey(User, on_delete=models.CASCADE)
     title = models.CharField(max_length=255)
-
+    collaborators = models.ManyToManyField(User,related_name='collaborators')
     def __str__(self):
         return self.title
\ No newline at end of file
diff --git a/api/permissions.py b/api/permissions.py
new file mode 100644
index 0000000..d94903b
--- /dev/null
+++ b/api/permissions.py
@@ -0,0 +1,8 @@
+from rest_framework import permissions
+
+class IsOwnerOrCollaborator(permissions.BasePermission):
+    """
+    custom permission to allow only creator and collaborator of a todo to view, edit and delete it. 
+    """
+    def has_object_permission(self, request, view, obj):
+        return (obj.creator == request.user) or (request.user in obj.collaborators.all())
\ No newline at end of file
diff --git a/api/serializers.py b/api/serializers.py
index ffd9d3a..353e0f5 100644
--- a/api/serializers.py
+++ b/api/serializers.py
@@ -1,6 +1,6 @@
 from rest_framework import serializers
 from .models import Todo
-
+from django.contrib.auth.models import User
 
 """
 TODO:
@@ -14,7 +14,6 @@ class TodoCreateSerializer(serializers.ModelSerializer):
     TODO:
     Currently, the /todo/create/ endpoint returns only 200 status code,
     after successful Todo creation.
-
     Modify the below code (if required), so that this endpoint would
     also return the serialized Todo data (id etc.), alongwith 200 status code.
     """
@@ -23,7 +22,30 @@ def save(self, **kwargs):
         user = self.context['request'].user
         title = data['title']
         todo = Todo.objects.create(creator=user, title=title)
+        return todo
     
     class Meta:
         model = Todo
         fields = ('id', 'title',)
+
+class UserObjectSerializer(serializers.ModelSerializer):
+
+    class Meta:
+        model = User
+        fields = ['username']
+
+class TodoSerializer(serializers.ModelSerializer):
+    collaborators = UserObjectSerializer(many=True, required = False)
+    creator = UserObjectSerializer(required = False)
+    class Meta:
+        model = Todo
+        fields = ['id', 'title', 'creator', 'collaborators',]
+class TodoUpateSerializer(serializers.ModelSerializer):
+    class Meta:
+        model = Todo
+        fields = ('id', 'title',)
+class CollaboratorSerializer(serializers.ModelSerializer):
+    collaborators = UserObjectSerializer(many=True)
+    class Meta:
+        model = Todo
+        fields = ['collaborators']
\ No newline at end of file
diff --git a/api/urls.py b/api/urls.py
index 72f4978..0332e8c 100644
--- a/api/urls.py
+++ b/api/urls.py
@@ -1,12 +1,18 @@
 from django.urls import path
-from .views import TodoCreateView
+from .views import TodoCreateView, TodoViewSet, CollaboratorViewSet
 
 """
 TODO:
 Add the urlpatterns of the endpoints, required for implementing
 Todo GET (List and Detail), PUT, PATCH and DELETE.
 """
+from rest_framework import routers
+
+router = routers.DefaultRouter()
+router.register(r'^todo', TodoViewSet)
+router.register(r'^todo', CollaboratorViewSet)
 
 urlpatterns = [
     path('todo/create/', TodoCreateView.as_view()),
-]
\ No newline at end of file
+]
+urlpatterns+=router.urls
\ No newline at end of file
diff --git a/api/views.py b/api/views.py
index d676c64..e46fb25 100644
--- a/api/views.py
+++ b/api/views.py
@@ -1,11 +1,16 @@
+from rest_framework.authtoken.models import Token
 from rest_framework import generics
 from rest_framework import permissions
 from rest_framework import status
 from rest_framework.response import Response
-from .serializers import TodoCreateSerializer
+from .serializers import TodoCreateSerializer, TodoSerializer, CollaboratorSerializer, TodoUpateSerializer
+from rest_framework import viewsets 
 from .models import Todo
-
-
+from django.contrib.auth.models import User
+from rest_framework.decorators import action
+from rest_framework.exceptions import PermissionDenied
+from rest_framework import mixins
+from .permissions import IsOwnerOrCollaborator
 """
 TODO:
 Create the appropriate View classes for implementing
@@ -18,7 +23,6 @@ class TodoCreateView(generics.GenericAPIView):
     TODO:
     Currently, the /todo/create/ endpoint returns only 200 status code,
     after successful Todo creation.
-
     Modify the below code (if required), so that this endpoint would
     also return the serialized Todo data (id etc.), alongwith 200 status code.
     """
@@ -30,6 +34,111 @@ def post(self, request):
         Creates a Todo entry for the logged in user.
         """
         serializer = self.get_serializer(data=request.data)
-        serializer.is_valid(raise_exception=True)
-        serializer.save()
-        return Response(status=status.HTTP_200_OK)
+        if serializer.is_valid(raise_exception=True):
+            instance = serializer.save()
+            return Response({
+                'id':instance.id,
+                'title':instance.title,
+            }, status=status.HTTP_200_OK)
+        else:
+            return Response(serializer.errors, status.HTTP_400_BAD_REQUEST)
+
+class TodoViewSet(mixins.RetrieveModelMixin, 
+                   mixins.UpdateModelMixin,
+                   mixins.DestroyModelMixin,
+                   mixins.ListModelMixin,
+                   viewsets.GenericViewSet):
+    permission_classes = (permissions.IsAuthenticated, IsOwnerOrCollaborator)
+    queryset = Todo.objects.all()
+    serializer_class = TodoSerializer
+    def get_serializer_class(self):
+        if self.action == 'update' or self.action == 'partial_update':
+            return TodoUpateSerializer
+        return TodoSerializer
+    def list(self, request, *args, **kwargs):
+        queryset1 = Todo.objects.filter(creator=request.user)
+        queryset2 = Todo.objects.filter(collaborators=request.user)
+        queryset = (queryset1 | queryset2).distinct()
+        serializer = self.get_serializer(queryset, many=True)
+        return Response(serializer.data, status=status.HTTP_200_OK)
+
+
+class CollaboratorViewSet(viewsets.ModelViewSet):
+    queryset = Todo.objects.all()
+    serializer_class = CollaboratorSerializer
+    @action(methods=['put'], detail=True, permission_classes=[permissions.IsAuthenticated, ], url_path='add-collaborator', url_name='add_collaborator')
+    def add_collaborator(self, request, pk=None):
+        try:
+            todo = Todo.objects.get(pk=pk)
+        except Todo.DoesNotExist:
+            return Response({'Error':'Invalid Todo Id'}, status=status.HTTP_400_BAD_REQUEST)
+        else:
+            if request.user == todo.creator:
+                try:
+                    collborators = request.data["collaborators"]
+                except KeyError:
+                    return Response({'Error':'Collaborator field not specified in request'}, status = status.HTTP_400_BAD_REQUEST)
+                else:
+                    collab_list = []
+                    b=False
+                    for collab in collborators:
+                        try:
+                            collab_name = collab['username']
+                        except KeyError:
+                            return Response({'Error':'No username provided'}, status = status.HTTP_400_BAD_REQUEST)
+                        else:
+                            try:
+                                new_collab = User.objects.get(username=collab_name)
+                            except User.DoesNotExist:
+                                return Response({'Invalid username':collab_name}, status=status.HTTP_400_BAD_REQUEST)
+                            if new_collab and new_collab != todo.creator:
+                                collab_list.append(new_collab)
+                            else:
+                                b=True
+                    todo.collaborators.add(*collab_list)
+                    todo.save()
+                    if b:
+                        return Response({'Denied':'Creator can not be added as collaborator'}, status=status.HTTP_206_PARTIAL_CONTENT)
+                    else:
+                        return Response({'Success':'Added collaborators successfully'}, status=status.HTTP_200_OK)
+                        
+            else:
+                raise PermissionDenied("You are not the creator of this Todo.")
+    @action(methods=['patch'], detail=True, permission_classes=[permissions.IsAuthenticated, ], url_path='delete-collaborator', url_name='delete_collaborator')
+    def delete_collaborator(self, request, pk=None):
+        try:
+            todo = Todo.objects.get(pk=pk)
+        except Todo.DoesNotExist:
+            return Response({"Error":'Invalid Todo Id'}, status=status.HTTP_400_BAD_REQUEST)
+        if request.user == todo.creator:
+            try:
+                collborators = request.data["collaborators"]
+            except KeyError:
+                return Response({'Error':'Collaborator field not specified in request'}, status = status.HTTP_400_BAD_REQUEST)
+            error_list = []
+            collab_list = []
+            collab_obj_list = todo.collaborators.all()
+            for collab in collab_obj_list:
+                collab_list.append(collab.username)
+            for collab in collborators:
+                try:
+                    collab_name = collab['username']
+                except KeyError:
+                    return Response({'Error':'No username provided'}, status = status.HTTP_400_BAD_REQUEST)
+                try:
+                    collab_rem_obj = User.objects.get(username=collab_name)
+                except User.DoesNotExist:
+                    return Response({'Invalid username':collab_name}, status=status.HTTP_400_BAD_REQUEST) 
+                if (collab_name in collab_list) and (collab_rem_obj):
+                    todo.collaborators.remove(collab_rem_obj)
+                    collab_list.remove(collab_name)
+                    todo.save()
+                else:
+                    error_list.append(collab_name)
+            if len(error_list):
+                return Response({"Following name(s) were not collaborating to the task":error_list}, status = status.HTTP_206_PARTIAL_CONTENT)
+            else:
+                return Response({"success":'Removed all the specified collaborators'}, status=status.HTTP_204_NO_CONTENT)     
+        else:
+            raise PermissionDenied("You are not the creator of this Todo.")
+        
\ No newline at end of file
diff --git a/authentication/migrations/0001_initial.py b/authentication/migrations/0001_initial.py
new file mode 100644
index 0000000..6c11d37
--- /dev/null
+++ b/authentication/migrations/0001_initial.py
@@ -0,0 +1,27 @@
+# Generated by Django 3.0.6 on 2020-05-10 11:38
+
+from django.conf import settings
+from django.db import migrations, models
+import django.db.models.deletion
+
+
+class Migration(migrations.Migration):
+
+    initial = True
+
+    dependencies = [
+        ('authtoken', '0002_auto_20160226_1747'),
+        migrations.swappable_dependency(settings.AUTH_USER_MODEL),
+    ]
+
+    operations = [
+        migrations.CreateModel(
+            name='Profile',
+            fields=[
+                ('id', models.AutoField(auto_created=True, primary_key=True, serialize=False, verbose_name='ID')),
+                ('name', models.CharField(max_length=150)),
+                ('token', models.OneToOneField(on_delete=django.db.models.deletion.CASCADE, to='authtoken.Token')),
+                ('user', models.OneToOneField(on_delete=django.db.models.deletion.CASCADE, to=settings.AUTH_USER_MODEL)),
+            ],
+        ),
+    ]
diff --git a/authentication/migrations/0002_delete_profile.py b/authentication/migrations/0002_delete_profile.py
new file mode 100644
index 0000000..5dcbdf6
--- /dev/null
+++ b/authentication/migrations/0002_delete_profile.py
@@ -0,0 +1,16 @@
+# Generated by Django 3.0.6 on 2020-05-11 06:18
+
+from django.db import migrations
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('authentication', '0001_initial'),
+    ]
+
+    operations = [
+        migrations.DeleteModel(
+            name='Profile',
+        ),
+    ]
diff --git a/authentication/serializers.py b/authentication/serializers.py
index 47264af..2320baf 100644
--- a/authentication/serializers.py
+++ b/authentication/serializers.py
@@ -1,23 +1,40 @@
 from rest_framework import serializers
 from django.contrib.auth import authenticate
 from django.contrib.auth.models import User
-
-
+from rest_framework.authtoken.models import Token
 class TokenSerializer(serializers.Serializer):
     token = serializers.CharField(max_length=500)
 
 
 class LoginSerializer(serializers.Serializer):
     # TODO: Implement login functionality
-    pass
+    username = serializers.CharField(required=True, allow_blank=False)
+    password = serializers.CharField(required=True, allow_blank=False)
 
 
-class RegisterSerializer(serializers.Serializer):
-    # TODO: Implement register functionality
-    pass
-
 
+class RegisterSerializer(serializers.ModelSerializer):
+    # TODO: Implement register functionality
+    name = serializers.CharField(source='first_name', max_length=150)
+    email = serializers.EmailField(max_length=255, required = True, allow_blank=False)
+    class Meta:
+        model = User
+        fields = ['name', 'email', 'username', 'password']
+        extra_kwargs = {'password':{'write_only':True}}
+    def create(self, validated_data):
+        user = User(
+            first_name = validated_data['first_name'],
+            username = validated_data['username'],
+            email = validated_data['email'],
+            password = validated_data['password'],
+        )
+        user.set_password((validated_data['password']))
+        user.save()
+        return user
+        
 class UserSerializer(serializers.ModelSerializer):
     # TODO: Implement the functionality to display user details
-    pass
-    
\ No newline at end of file
+    name = serializers.CharField(source='first_name', max_length=150, required=False)
+    class Meta:
+        model = User
+        fields = ['id', 'name', 'email', 'username']
\ No newline at end of file
diff --git a/authentication/views.py b/authentication/views.py
index d748434..df17c84 100644
--- a/authentication/views.py
+++ b/authentication/views.py
@@ -1,8 +1,11 @@
 from rest_framework import permissions
 from rest_framework import generics
 from rest_framework import status
+from rest_framework.views import APIView
+from django.contrib.auth.models import User
 from rest_framework.response import Response
 from rest_framework.authtoken.models import Token
+from django.contrib.auth import authenticate
 from .serializers import (
     LoginSerializer, RegisterSerializer, UserSerializer, TokenSerializer)
 
@@ -21,16 +24,40 @@ class LoginView(generics.GenericAPIView):
     Implement login functionality, taking username and password
     as input, and returning the Token.
     """
-    pass
+    authentication_classes = ()
+    permission_classes = ()
+    serializer_class = LoginSerializer
+    def post(self, request, *args, **kwargs):
+        serializer = self.get_serializer(data=request.data)
+        if serializer.is_valid(raise_exception=True):
+            username=serializer.data['username']
+            password=serializer.data['password']
+            user = authenticate(username=username, password=password)
+            if user:
+                token=create_auth_token(user)
+                return Response({"token":token.key},status=status.HTTP_200_OK)
+            else:
+                return Response({"error":"Wrong credentials"}, status = status.HTTP_400_BAD_REQUEST)
+        else:
+            return Response(serializer.errors, status=status.HTTP_400_BAD_REQUEST)
 
-
-class RegisterView(generics.GenericAPIView):
+class RegisterView(generics.CreateAPIView):
     """
     TODO:
     Implement register functionality, registering the user by
     taking his details, and returning the Token.
     """
-    pass
+    authentication_classes = ()
+    permission_classes = ()
+    serializer_class = RegisterSerializer
+    def create(self, request, *args, **kwargs):
+        serializer = self.get_serializer(data=request.data)
+        if serializer.is_valid(raise_exception=True):
+            self.perform_create(serializer)
+            token=create_auth_token(serializer.instance)
+            return Response({'token':token.key}, status=status.HTTP_200_OK)
+        else:
+            return Response(serializer.errors, status=status.HTTP_400_BAD_REQUEST)
 
 
 class UserProfileView(generics.RetrieveAPIView):
@@ -39,4 +66,20 @@ class UserProfileView(generics.RetrieveAPIView):
     Implement the functionality to retrieve the details
     of the logged in user.
     """
-    pass
\ No newline at end of file
+    serializer_class = UserSerializer
+    def get(self, request, *args, **kwargs):
+        try:
+            header=request.headers['Authorization']
+        except Exception:
+            return Response({
+            "detail": "Authentication credentials were not provided."
+            }, status=status.HTTP_401_UNAUTHORIZED)
+        else:
+            token = header.split(' ')[1]
+            try:
+                user = Token.objects.get(key=token).user
+            except Token.DoesNotExist:
+                return Response({"detail":"Invalid Token"},status=status.HTTP_404_NOT_FOUND)
+            else:
+                serializer = self.get_serializer(user)
+                return Response(serializer.data, status=status.HTTP_200_OK)
diff --git a/todo/settings.py b/todo/settings.py
index 8359271..d1a9e20 100644
--- a/todo/settings.py
+++ b/todo/settings.py
@@ -45,7 +45,8 @@
     'rest_framework.authtoken',
     'drf_yasg',
     'corsheaders',
-    'api'
+    'api',
+    'authentication',
 ]
 
 MIDDLEWARE = [