diff --git a/README.md b/README.md
index f571830f..c0c581fe 100644
--- a/README.md
+++ b/README.md
@@ -52,11 +52,11 @@ Volg deze stappen om de backend van het project op te zetten:
     ```
 6. Voer het `fill_database_mock.py` script uit als een module om de database te vullen met mock data:
     ```bash
-    python -m db.fill_database_mock
+    python fill_database_mock.py
     ```
     Je kan ook een lege databank initialiseren met het `create_database_tables.py` script als volgt:
     ```bash
-    python -m db.create_database_tables
+    python create_database_tables.py
     ```
     *Opgelet: beide scripts zullen de huidige databankinhoud verwijderen indien die bestaat en daarna de tabellen opnieuw aanmaken.*
 7. Start de API door het `app.py` script uit te voeren:
diff --git a/frontend/package-lock.json b/frontend/package-lock.json
index 52417613..dcd57d9b 100644
--- a/frontend/package-lock.json
+++ b/frontend/package-lock.json
@@ -3014,20 +3014,6 @@
       "integrity": "sha512-OO0pH2lK6a0hZnAdau5ItzHPI6pUlvI7jMVnxUQRtw4owF2wk8lOSabtGDCTP4Ggrg2MbGnWO9X8K1t4+fGMDw==",
       "dev": true
     },
-    "node_modules/fsevents": {
-      "version": "2.3.3",
-      "resolved": "https://registry.npmjs.org/fsevents/-/fsevents-2.3.3.tgz",
-      "integrity": "sha512-5xoDfX+fL7faATnagmWPpbFtwh/R77WmMMqqHGS65C3vvB0YHrgF+B1YmZ3441tMj5n63k0212XNoJwzlhffQw==",
-      "dev": true,
-      "hasInstallScript": true,
-      "optional": true,
-      "os": [
-        "darwin"
-      ],
-      "engines": {
-        "node": "^8.16.0 || ^10.6.0 || >=11.0.0"
-      }
-    },
     "node_modules/function-bind": {
       "version": "1.1.2",
       "resolved": "https://registry.npmjs.org/function-bind/-/function-bind-1.1.2.tgz",
diff --git a/frontend/src/components/ProjectStudentComponent.tsx b/frontend/src/components/ProjectStudentComponent.tsx
index b0d78283..b18aa098 100644
--- a/frontend/src/components/ProjectStudentComponent.tsx
+++ b/frontend/src/components/ProjectStudentComponent.tsx
@@ -10,10 +10,10 @@ import {useTranslation} from 'react-i18next';
 
 export default function ProjectStudentComponent(props: { project: ProjectStudent }): JSX.Element {
 
+
     // true als er een groep is, anders false.
     const is_in_group = props.project.groupMembers && props.project.groupMembers.length > 0;
 
-
     const { t } = useTranslation();
 
     return (
diff --git a/frontend/src/components/ProjectTeacherComponent.tsx b/frontend/src/components/ProjectTeacherComponent.tsx
index 2a658f81..de64029b 100644
--- a/frontend/src/components/ProjectTeacherComponent.tsx
+++ b/frontend/src/components/ProjectTeacherComponent.tsx
@@ -10,6 +10,7 @@ import SimpleTests from "./SimpleTests/SimpleTests.tsx";
 import {TeacherOrStudent} from "./SimpleTests/TeacherOrStudentEnum.tsx";
 import Calendar from "react-calendar";
 import {useTranslation} from 'react-i18next';
+import {RegularButton} from "./RegularButton.tsx";
 
 // SimpleTests
 const CHECK_SIMPLE_TESTS = false
@@ -54,6 +55,10 @@ export function ProjectTeacherComponent(props: { project: ProjectTeacher }): JSX
     const [data, setData] = useState<object>(calledData);
     const [hasChanged, setHasChanged] = useState(false);
 
+    const save = () => {
+        // TODO save button
+    }
+
     return (
         <div className={"create-project"}>
             {/* PROJECT NAME FIELD */}
@@ -181,7 +186,8 @@ export function ProjectTeacherComponent(props: { project: ProjectTeacher }): JSX
                                         <input type="checkbox"/>
                                     </div>
                                     <div className="field-body">
-                                        <label className="label is-fullwidth">{t('create_project.teamwork.changes')}</label>
+                                        <label
+                                            className="label is-fullwidth">{t('create_project.teamwork.changes')}</label>
                                     </div>
                                 </div>
                                 <br/>
@@ -215,8 +221,11 @@ export function ProjectTeacherComponent(props: { project: ProjectTeacher }): JSX
                         }
                     </label>
                 </div>
+                <div className={"mx-5"}>
+                    <RegularButton placeholder={t('create_project.save_button')} add={false} onClick={save}/>
+                </div>
             </div>
         </div>
     )
         ;
-}
\ No newline at end of file
+}
diff --git a/frontend/src/components/Settings.tsx b/frontend/src/components/Settings.tsx
index 313dc0b5..d55e7c2e 100644
--- a/frontend/src/components/Settings.tsx
+++ b/frontend/src/components/Settings.tsx
@@ -7,7 +7,7 @@ import {MdLanguage, MdOutlineKeyboardArrowDown} from "react-icons/md";
 import useAuth from "../hooks/useAuth.ts";
 import {User} from "../utils/ApiInterfaces.ts";
 import {useTranslation} from "react-i18next";
-import i18n from "../i18n.tsx";
+import {modify_language} from "../utils/api/User.ts";
 
 function DropdownLanguage(): JSX.Element {
     const [isOpen, setIsOpen] = useState<boolean>(false);
@@ -35,7 +35,7 @@ function DropdownLanguage(): JSX.Element {
                     <a
                         className="dropdown-item"
                         onClick={() => {
-                            void i18n.changeLanguage("en");
+                            modify_language("en")
                             toggle()
                         }}
                     >
@@ -44,7 +44,7 @@ function DropdownLanguage(): JSX.Element {
                     <a
                         className="dropdown-item"
                         onClick={() => {
-                            void i18n.changeLanguage("nl");
+                            modify_language("nl")
                             toggle()
                         }}
                     >
diff --git a/frontend/src/components/Sidebar.tsx b/frontend/src/components/Sidebar.tsx
index fb1f269e..300dcf93 100644
--- a/frontend/src/components/Sidebar.tsx
+++ b/frontend/src/components/Sidebar.tsx
@@ -16,7 +16,7 @@ export function Sidebar(props: {home: string, buttons?: SidebarButton[]}): JSX.E
     if (buttons == undefined) {
         buttons = [SidebarButton.COURSES, SidebarButton.PROJECTS];
     }
-    
+
     return (
         <>
             <aside className={"menu is-flex is-flex-direction-column is-justify-content-space-between"}>
diff --git a/frontend/src/dataloaders/AdminLoader.ts b/frontend/src/dataloaders/AdminLoader.ts
index 86ed6ba4..df343c4a 100644
--- a/frontend/src/dataloaders/AdminLoader.ts
+++ b/frontend/src/dataloaders/AdminLoader.ts
@@ -1,4 +1,4 @@
-import apiFetch from "../utils/ApiFetch.ts";
+import apiFetch, {ApiFetchResponse} from "../utils/ApiFetch.ts";
 import {Backend_user} from "../utils/BackendInterfaces.ts";
 import {mapUser} from "../utils/ApiTypesMapper.ts";
 import {User} from "../utils/ApiInterfaces.ts";
@@ -17,8 +17,11 @@ function filter_on_role(users: User[], role: string): User[] {
 }
 
 export default async function adminLoader(): Promise<AdminLoaderObject> {
-    const users_backend: Backend_user[] = (await apiFetch("/users")) as Backend_user[];
-    const users: User[] = users_backend.map((user) => mapUser(user));
+    const users_backend: ApiFetchResponse<Backend_user[]> = await apiFetch<Backend_user[]>("/users");
+    if (!users_backend.ok) {
+        // TODO error handling
+    }
+    const users = users_backend.content.map((user) => mapUser(user));
     const students = filter_on_role(users, "STUDENT");
     const teachers = filter_on_role(users, "TEACHER");
     const admins = filter_on_role(users, "ADMIN");
diff --git a/frontend/src/dataloaders/LoginLoader.ts b/frontend/src/dataloaders/LoginLoader.ts
index 76c4405d..48f58576 100644
--- a/frontend/src/dataloaders/LoginLoader.ts
+++ b/frontend/src/dataloaders/LoginLoader.ts
@@ -17,9 +17,11 @@ const isUser = (data?: Backend_user) => {
 export default async function loginLoader(): Promise<loginLoaderObject> {
     const token = localStorage.getItem('token')
     if (token) {
-        const user = (await apiFetch('/user')) as Backend_user;
-        if (isUser(user)) {
-            return {user: mapUser(user)}
+        const user_request = (await apiFetch<Backend_user>('/user'));
+        if (user_request.ok && isUser(user_request.content)) {
+            return {user: mapUser(user_request.content)}
+        }else{
+            // TODO error handling
         }
     }
     return {user: undefined}
diff --git a/frontend/src/dataloaders/ProjectsStudentLoader.ts b/frontend/src/dataloaders/ProjectsStudentLoader.ts
index e8bb88dc..758c0c46 100644
--- a/frontend/src/dataloaders/ProjectsStudentLoader.ts
+++ b/frontend/src/dataloaders/ProjectsStudentLoader.ts
@@ -45,12 +45,15 @@ export async function LoadProjectsForStudent(filter_on_current: boolean = false,
     const project_ids = projects.map(project => project.project_id);
 
     const apiGroups = project_ids.map(async project_id => {
-        const apiGroup = await apiFetch(`/projects/${project_id}/group`) as Backend_group;
+        const apiGroupData = await apiFetch<Backend_group>(`/projects/${project_id}/group`);
+        if (!apiGroupData.ok){
+            // TODO: error handling
+        }
+        const apiGroup = apiGroupData.content;
         if (apiGroup) {
             return mapGroup(apiGroup);
-        } else {
-            return null
         }
+        return null;
     })
 
     const groups = (await Promise.all(apiGroups))
@@ -58,14 +61,21 @@ export async function LoadProjectsForStudent(filter_on_current: boolean = false,
     const group_ids = groups_without_null.map(group => group?.group_id);
 
     const submissionPromises: Promise<Submission>[] = group_ids.map(async group_id => {
-        const apiSubmission = await apiFetch(`/groups/${group_id}/submission`) as Backend_submission;
-        return mapSubmission(apiSubmission);
+        const apiSubmission = await apiFetch<Backend_submission>(`/groups/${group_id}/submission`);
+        if (!apiSubmission.ok) {
+            // TODO error handling
+        }
+        return mapSubmission(apiSubmission.content);
     });
 
     const submissions: Submission[] = (await Promise.all(submissionPromises));
 
     const groupMemberIdsPromises: Promise<groupInfo>[] = groups_without_null.map(async group => {
-        const members = await apiFetch(`/groups/${group.group_id}/members`) as memberInfo[]
+        const membersData = await apiFetch<memberInfo[]>(`/groups/${group.group_id}/members`)
+        if (!membersData.ok) {
+            // TODO error handling
+        }
+        const members = membersData.content;
         return {group_id: group.group_id, project_id: group.project_id, member_ids: members};
     });
 
@@ -73,8 +83,11 @@ export async function LoadProjectsForStudent(filter_on_current: boolean = false,
 
     const groupMembersPromises: Promise<groupInfo>[] = groupMemberInfo.map(async (groupinfo) => {
         const memberPromises = groupinfo.member_ids.map(async (memberId) => {
-            const apiMember = await apiFetch(`/users/${memberId.id}`) as Backend_user;
-            return mapUser(apiMember);
+            const apiMemberData = await apiFetch<Backend_user>(`/users/${memberId.id}`);
+            if (!apiMemberData.ok) {
+                // TODO error handling
+            }
+            return mapUser(apiMemberData.content);
         });
         const users = await Promise.all(memberPromises);
         return {
diff --git a/frontend/src/dataloaders/loader_helpers/SharedFunctions.ts b/frontend/src/dataloaders/loader_helpers/SharedFunctions.ts
index 9a227671..bf64859a 100644
--- a/frontend/src/dataloaders/loader_helpers/SharedFunctions.ts
+++ b/frontend/src/dataloaders/loader_helpers/SharedFunctions.ts
@@ -47,11 +47,17 @@ export async function coursesLoader(role: teacherStudentRole, course_id?: number
     }
 
     const teachers = (await Promise.all(courses.map(async course => {
-        const teacher_ids = await apiFetch(`/subjects/${course.subject_id}/teachers`) as TeacherIdInfo[];
-
+        const teacher_ids_data = await apiFetch<TeacherIdInfo[]>(`/subjects/${course.subject_id}/teachers`);
+        if (!teacher_ids_data.ok){
+            // TODO error handling
+        }
+        const teacher_ids = teacher_ids_data.content
         const teachers_promises = teacher_ids.map(async teacher_id => {
-            const user = await apiFetch(`/users/${teacher_id.id}`) as Backend_user
-            return mapUser(user);
+            const userData = await apiFetch<Backend_user>(`/users/${teacher_id.id}`);
+            if (!userData.ok){
+                // TODO error handling
+            }
+            return mapUser(userData.content);
         });
 
         const teachers = await Promise.all(teachers_promises);
@@ -121,12 +127,18 @@ export interface projectsAndSubjects {
 }
 
 export async function getAllProjectsAndSubjects(role: teacherStudentRole, filter_on_current: boolean = false): Promise<projectsAndSubjects> {
-    const apiSubjects = (await apiFetch(`/${role}/subjects`)) as Backend_Subject[];
-    const apiProjects = (await apiFetch(`/${role}/projects`)) as Backend_Project[];
-    let projects: Project[] = mapProjectList(apiProjects);
+    const apiProjects = (await apiFetch<Backend_Project[]>(`/${role}/projects`));
+    const apiSubjects = (await apiFetch<Backend_Subject[]>(`/${role}/subjects`));
+
+    if (!apiProjects.ok || !apiSubjects.ok) {
+        // TODO error handling
+        // throw ...
+    }
+    let projects = mapProjectList(apiProjects.content);
     if (filter_on_current) {
         projects = projects.filter(project => project.project_visible && !project.project_archived)
     }
-    const subjects: Subject[] = mapSubjectList(apiSubjects);
+
+    const subjects = mapSubjectList(apiSubjects.content);
     return {projects, subjects}
 }
diff --git a/frontend/src/dataloaders/projectsTeacherLoader.ts b/frontend/src/dataloaders/projectsTeacherLoader.ts
index f1ccbae8..5e710e4e 100644
--- a/frontend/src/dataloaders/projectsTeacherLoader.ts
+++ b/frontend/src/dataloaders/projectsTeacherLoader.ts
@@ -31,8 +31,11 @@ export async function LoadProjectsForTeacher(filter_on_current: boolean = false,
     }
 
     const groupPromises: Promise<Group[][]> = Promise.all(projects.map(async project => {
-        const groups = await apiFetch(`/projects/${project.project_id}/groups`) as Backend_group[];
-        return mapGroupList(groups);
+        const groups = await apiFetch<Backend_group[]>(`/projects/${project.project_id}/groups`);
+        if (!groups.ok) {
+            // TODO: error handling
+        }
+        return mapGroupList(groups.content);
     }));
 
     const statistics: { [key: number]: number } = {
@@ -47,9 +50,13 @@ export async function LoadProjectsForTeacher(filter_on_current: boolean = false,
         let amount = 0
         for (const group of groupArray) {
             try {
-                const submissionBackend = await apiFetch(`/groups/${group.group_id}/submission`) as Backend_submission;
-                const submission = mapSubmission(submissionBackend);
-                if (submission) {
+                const submissionData = await apiFetch<Backend_submission>(`/groups/${group.group_id}/submission`);
+                if (!submissionData.ok){
+                    // TODO error handling
+                }
+                const submissionBackend = submissionData.content
+                if (submissionBackend) {
+                    const submission = mapSubmission(submissionData.content)
                     console.log(submission)
                     statistics[submission.submission_state] += 1;
                     amount++;
diff --git a/frontend/src/pages/login/LoginScreen.tsx b/frontend/src/pages/login/LoginScreen.tsx
index 7b9ec838..b088e9c1 100644
--- a/frontend/src/pages/login/LoginScreen.tsx
+++ b/frontend/src/pages/login/LoginScreen.tsx
@@ -3,8 +3,8 @@ import {Navigate, useLocation, useRouteLoaderData} from 'react-router-dom';
 import useAuth from "../../hooks/useAuth.ts";
 import loginLoader, {LOGIN_ROUTER_ID, loginLoaderObject} from "../../dataloaders/LoginLoader.ts";
 import LoginForm from "../../components/authentication/LoginForm.tsx";
-import {DEBUG} from "../root.tsx";
 import {Token, User} from "../../utils/ApiInterfaces.ts";
+import {post_ticket} from "../../utils/api/Login.ts";
 
 interface location_type {
     search?: { ticket?: string },
@@ -12,26 +12,18 @@ interface location_type {
     pathname: string
 }
 
-const ticketLogin = async (ticket: string, setUser: React.Dispatch<React.SetStateAction<User | undefined>>) => {
-    let url = '/api/login?ticket=' + ticket
-    if (DEBUG) {
-        url = 'http://127.0.0.1:8000/api/login?ticket=' + ticket
-    }
-    const token = await (await fetch(url, {method: 'POST', headers: {'Content-Type': 'application/json'}}))
-        .json() as Token
-
-    if (token.token) {
+async function ticketLogin (ticket: string, setUser: React.Dispatch<React.SetStateAction<User | undefined>>) {
+    const token: Token | undefined = await post_ticket(ticket)
+    if (token?.token) {
         localStorage.setItem('token', token.token)
         const result: loginLoaderObject = await loginLoader()
         if (result.user) {
             setUser(result.user)
-        }else{
+        } else {
             localStorage.removeItem('token')
             setUser(undefined)
         }
     }
-
-    return token;
 }
 
 export default function LoginScreen(): JSX.Element {
@@ -53,9 +45,12 @@ export default function LoginScreen(): JSX.Element {
         // If the saved token is valid => the user will be logged in
         if (data && data.user) {
             setUser(data.user)
-        }
-        else if (!user && ticket) {
-            void ticketLogin(ticket, setUser);
+        } else if (!user && ticket) {
+            try {
+                void ticketLogin(ticket, setUser);
+            } catch (error) {
+                console.log("Ticket wasn't accepted")
+            }
         }
     }, [data, setUser, ticket, user]);
 
diff --git a/frontend/src/pages/teacher/CreateCourse.tsx b/frontend/src/pages/teacher/CreateCourse.tsx
index 8103d18f..2167a8f9 100644
--- a/frontend/src/pages/teacher/CreateCourse.tsx
+++ b/frontend/src/pages/teacher/CreateCourse.tsx
@@ -3,12 +3,19 @@ import Inputfield from "../../components/Inputfield.tsx";
 import {Header} from "../../components/Header.tsx";
 import {Sidebar} from "../../components/Sidebar.tsx";
 import {RegularButton} from "../../components/RegularButton.tsx";
-import { useTranslation } from 'react-i18next';
+import {useTranslation} from 'react-i18next';
+import {createSubject} from "../../utils/api/Teacher.ts";
 
 export default function CreateCourse(): JSX.Element {
-    const [projectName, setProjectName] = useState<string>("");
+    const [courseName, setCourseName] = useState<string>("");
 
-    const { t } = useTranslation();
+    const {t} = useTranslation();
+
+    const createCourse = () => {
+        // todo: what after succes/failure
+        // Default: archived false
+        void createSubject(courseName)
+    }
 
     return (
         <>
@@ -25,13 +32,15 @@ export default function CreateCourse(): JSX.Element {
                             <label className="label">{t('create_course.name.tag')}</label>
                         </div>
                         <div className="field-body field">
-                            <Inputfield placeholder={t('create_course.name.placeholder')} value={projectName}
-                                        setValue={setProjectName}/>
+                            <Inputfield placeholder={t('create_course.name.placeholder')} value={courseName}
+                                        setValue={setCourseName}/>
                         </div>
                     </div>
                     <div className={"is-flex is-justify-content-center"}>
                         {/*Waiting for the post requests to implement the on click*/}
-                        <RegularButton placeholder={t('create_course.confirm')} add={false} onClick={() => {}}/>
+                        <RegularButton placeholder={t('create_course.confirm')} add={false} onClick={() => {
+                            createCourse
+                        }}/>
                     </div>
                 </div>
             </div>
diff --git a/frontend/src/pages/teacher/CreateProject.tsx b/frontend/src/pages/teacher/CreateProject.tsx
index 37a7d294..149275e5 100644
--- a/frontend/src/pages/teacher/CreateProject.tsx
+++ b/frontend/src/pages/teacher/CreateProject.tsx
@@ -44,6 +44,7 @@ export function CreateProject(): JSX.Element {
                     <Sidebar home={"teacher"}/>
                 </div>
                 <div className={"student-main my-3 is-flex is-flex-direction-column"}>
+                    {/* TODO: Should be moved to same class as the hooks*/}
                     <div className={"mx-5"}>
                         <RegularButton placeholder={t('create_project.save_button')} add={false} onClick={() => {}}/>
                     </div>
diff --git a/frontend/src/utils/ApiFetch.ts b/frontend/src/utils/ApiFetch.ts
index c9232cbd..bcd6c140 100644
--- a/frontend/src/utils/ApiFetch.ts
+++ b/frontend/src/utils/ApiFetch.ts
@@ -1,7 +1,12 @@
 import {DEBUG} from "../pages/root.tsx";
 
+export interface ApiFetchResponse<Type>{
+    ok: boolean,
+    status_code: number,
+    content: Type
+}
 
-const ApiFetch = async (url: string, options?: RequestInit) => {
+export async function ApiFetch<Type> (url: string, options?: RequestInit) {
     if (typeof options === 'undefined') {
         options = {}
     }
@@ -18,7 +23,12 @@ const ApiFetch = async (url: string, options?: RequestInit) => {
     if (DEBUG) {
         url = "http://127.0.0.1:8000" + url;
     }
-    return (await fetch(url, options)).json()
+    const response = await fetch(url, options)
+    return {
+        ok: response.ok,
+        status_code: response.status,
+        content: response.status !== 204 ? await response.json() as Type : {}
+    } as ApiFetchResponse<Type>
 }
 
 export default ApiFetch
diff --git a/frontend/src/utils/ApiTypesMapper.ts b/frontend/src/utils/ApiTypesMapper.ts
index 404102fd..71532883 100644
--- a/frontend/src/utils/ApiTypesMapper.ts
+++ b/frontend/src/utils/ApiTypesMapper.ts
@@ -7,18 +7,22 @@ import {
     Backend_user
 } from "./BackendInterfaces.ts";
 
+export function mapSubject(subjectData: Backend_Subject): Subject{
+    return {
+        subject_id: subjectData.id,
+        subject_name: subjectData.name,
+    }
+}
+
 export function mapSubjectList(subjectList: Backend_Subject[]): Subject[] {
     if (!Array.isArray(subjectList)) {
         throw new Error('projectList is not an array');
     }
-    return subjectList.map(subjectData => ({
-        subject_id: subjectData.id,
-        subject_name: subjectData.name,
-    }));
+    return subjectList.map(subjectData => mapSubject(subjectData));
 }
 
-export function mapProjectList(projectList: Backend_Project[]): Project[] {
-    return projectList.map(projectData => ({
+export function mapProject(projectData: Backend_Project): Project{
+    return {
         project_id: projectData.id,
         project_name: projectData.name,
         project_deadline: projectData.deadline,
@@ -28,7 +32,11 @@ export function mapProjectList(projectList: Backend_Project[]): Project[] {
         project_visible: projectData.visible,
         project_max_students: projectData.max_students,
         subject_id: projectData.subject_id,
-    }));
+    }
+}
+
+export function mapProjectList(projectList: Backend_Project[]): Project[] {
+    return projectList.map(projectData => mapProject(projectData));
 }
 
 export function mapSubmission(submission: Backend_submission): Submission {
diff --git a/frontend/src/utils/InputInterfaces.ts b/frontend/src/utils/InputInterfaces.ts
new file mode 100644
index 00000000..3da5c7fb
--- /dev/null
+++ b/frontend/src/utils/InputInterfaces.ts
@@ -0,0 +1,16 @@
+import {Value} from "../types/project.ts";
+
+export interface ProjectInput{
+    name: string,
+    deadline: Value,
+    archived: boolean,
+    description: string,
+    requirements: string,
+    visible: boolean,
+    max_students: number,
+}
+
+export interface SubjectInput{
+    name: string;
+    archived: boolean
+}
diff --git a/frontend/src/utils/api/Groups.ts b/frontend/src/utils/api/Groups.ts
new file mode 100644
index 00000000..109e884a
--- /dev/null
+++ b/frontend/src/utils/api/Groups.ts
@@ -0,0 +1,11 @@
+import ApiFetch from "../ApiFetch.ts";
+
+export function joinGroup(groupId: number): void {
+    void ApiFetch(`/groups/${groupId}/join`,
+        {method: 'POST', headers: {'Content-Type': 'application/json'}});
+}
+
+export function leaveGroup(groupId: number): void {
+    void ApiFetch(`/groups/${groupId}/leave`,
+        {method: 'POST', headers: {'Content-Type': 'application/json'}});
+}
\ No newline at end of file
diff --git a/frontend/src/utils/api/Login.ts b/frontend/src/utils/api/Login.ts
new file mode 100644
index 00000000..84b9be54
--- /dev/null
+++ b/frontend/src/utils/api/Login.ts
@@ -0,0 +1,21 @@
+import {DEBUG} from "../../pages/root.tsx";
+import {Token} from "../ApiInterfaces.ts";
+
+export async function post_ticket(ticket: string): Promise<Token | undefined> {
+    let url = '/api/login?ticket=' + ticket;
+    if (DEBUG) {
+        url = 'http://127.0.0.1:8000/api/login?ticket=' + ticket;
+    }
+
+    const tokenData = await fetch(url, {
+        method: 'POST',
+        headers: {
+            'Content-Type': 'application/json'
+        },
+    })
+    if (tokenData.ok) {
+        return await tokenData.json() as Token
+    }
+
+    return undefined
+}
\ No newline at end of file
diff --git a/frontend/src/utils/api/Project.ts b/frontend/src/utils/api/Project.ts
new file mode 100644
index 00000000..09e12739
--- /dev/null
+++ b/frontend/src/utils/api/Project.ts
@@ -0,0 +1,31 @@
+import apiFetch from "../ApiFetch.ts";
+import {ProjectInput} from "../InputInterfaces.ts";
+import {Backend_group, Backend_Project} from "../BackendInterfaces.ts";
+import {mapGroup} from "../ApiTypesMapper.ts";
+import {Group} from "../ApiInterfaces.ts";
+
+export async function project_create_group(project_id: number): Promise<Group> {
+    const groupData = await apiFetch<Backend_group>(`/projects/${project_id}/groups`, {
+        method: 'POST',
+        headers: {
+            'Content-Type': 'application/json'
+        }
+    });
+    if (groupData.ok) {
+        return mapGroup(groupData.content);
+    }
+    // TODO: error handling
+    throw groupData.status_code
+}
+
+export async function update_project(project_id: number, projectInput: ProjectInput): Promise<boolean> {
+    const projectData = await apiFetch<Backend_Project>(`/projects/${project_id}`, {
+        method: 'PUT',
+        headers: {
+            'Content-Type': 'application/json'
+        },
+        body: JSON.stringify(projectInput)
+    });
+    return projectData.ok;
+}
+
diff --git a/frontend/src/utils/api/Student.ts b/frontend/src/utils/api/Student.ts
new file mode 100644
index 00000000..57da2922
--- /dev/null
+++ b/frontend/src/utils/api/Student.ts
@@ -0,0 +1,13 @@
+import apiFetch from "../ApiFetch.ts";
+
+export function join_subject(subjectId: number): void{
+    void apiFetch(`/student/subjects/${subjectId}/join`, {
+        method: 'POST'
+    });
+}
+
+export function leave_subject(subjectId: number): void{
+    void apiFetch(`/student/subjects/${subjectId}/leave`, {
+        method: 'POST'
+    });
+}
\ No newline at end of file
diff --git a/frontend/src/utils/api/Subject.ts b/frontend/src/utils/api/Subject.ts
new file mode 100644
index 00000000..527b9600
--- /dev/null
+++ b/frontend/src/utils/api/Subject.ts
@@ -0,0 +1,32 @@
+import {ProjectInput, SubjectInput} from "../InputInterfaces.ts";
+import ApiFetch from "../ApiFetch.ts";
+import {Backend_Project} from "../BackendInterfaces.ts";
+import {Project} from "../ApiInterfaces.ts";
+import {mapProject} from "../ApiTypesMapper.ts";
+
+export async function subject_create_project(subjectId: number, projectInput: ProjectInput): Promise<Project> {
+    const projectData = (await ApiFetch<Backend_Project>(`/subjects/${subjectId}/projects`, {
+        method: 'POST',
+        headers: {
+            'Content-Type': 'application/json'
+        },
+        body: JSON.stringify(projectInput)
+    }));
+    if (projectData.ok) {
+        return mapProject(projectData.content);
+    }else{
+        // TODO: error handling
+        throw projectData.status_code
+    }
+}
+
+export async function update_subject(subjectId: number, subjectInput: SubjectInput){
+    const subjectData = (await ApiFetch<Backend_Project>(`/subjects/${subjectId}`, {
+        method: 'PUT',
+        headers: {
+            'Content-Type': 'application/json'
+        },
+        body: JSON.stringify(subjectInput)
+    }));
+    return subjectData.ok;
+}
\ No newline at end of file
diff --git a/frontend/src/utils/api/Submission.ts b/frontend/src/utils/api/Submission.ts
new file mode 100644
index 00000000..07b682fd
--- /dev/null
+++ b/frontend/src/utils/api/Submission.ts
@@ -0,0 +1,15 @@
+/* TODO: When this function is implemented --> so that type file is known
+export async function make_submission(groupId: number, file: File) {
+const submissionData = (await apiFetch<Backend_submission>(`/groups/${groupId}/submission`,
+    {
+        headers: {
+            'Content-Type': 'multipart/form-data'
+        },
+        method: 'POST',
+        body: JSON.stringify({file: file})
+    }));
+if (submissionData.ok){
+    return mapSubmission(submissionData.content)
+}
+}
+ */
diff --git a/frontend/src/utils/api/Teacher.ts b/frontend/src/utils/api/Teacher.ts
new file mode 100644
index 00000000..48c95257
--- /dev/null
+++ b/frontend/src/utils/api/Teacher.ts
@@ -0,0 +1,22 @@
+import {Backend_Subject} from "../BackendInterfaces.ts";
+import apiFetch from "../ApiFetch.ts";
+import {Subject} from "../ApiInterfaces.ts";
+import {mapSubject} from "../ApiTypesMapper.ts";
+
+export async function createSubject(name: string): Promise<Subject> {
+    const subjectData = (await apiFetch<Backend_Subject>('/teacher/subjects',
+        {
+            headers: {
+                'Content-Type': 'application/json'
+            },
+            method: 'POST',
+            body: JSON.stringify({name: name, archived: false})
+        }));
+
+    if (subjectData.ok){
+        return mapSubject(subjectData.content);
+    }else{
+        // TODO: error handling
+        throw subjectData.status_code
+    }
+}
\ No newline at end of file
diff --git a/frontend/src/utils/api/User.ts b/frontend/src/utils/api/User.ts
new file mode 100644
index 00000000..0d58dc76
--- /dev/null
+++ b/frontend/src/utils/api/User.ts
@@ -0,0 +1,18 @@
+import apiFetch from "../ApiFetch.ts";
+import i18n from "../../i18n.tsx";
+
+export function modify_language(language: string): void {
+    void i18n.changeLanguage(language);
+    void apiFetch(`/user?language=${language.toUpperCase()}`, {
+        method: 'PUT'
+    });
+}
+
+export function modify_roles(userId: number, roles: string[]): void {
+    console.log(JSON.stringify(roles))
+    void apiFetch(`/users/${userId}?roles=${JSON.stringify({roles})}`, {
+        method: 'PUT',
+        headers: {'Content-Type': 'application/json'},
+        body: JSON.stringify(roles)
+    });
+}