diff --git a/src/components/tasks/add-task.vue b/src/components/tasks/add-task.vue
index 2a4b2e3e8..ef45ca884 100644
--- a/src/components/tasks/add-task.vue
+++ b/src/components/tasks/add-task.vue
@@ -200,7 +200,7 @@ function handleEnter(e: KeyboardEvent) {
 }
 
 function focusTaskInput() {
-	newTaskInput.value.focus()
+	newTaskInput.value?.focus()
 }
 
 defineExpose({
diff --git a/src/components/tasks/partials/editLabels.vue b/src/components/tasks/partials/editLabels.vue
index bc218519a..0e2858225 100644
--- a/src/components/tasks/partials/editLabels.vue
+++ b/src/components/tasks/partials/editLabels.vue
@@ -117,7 +117,7 @@ async function removeLabel(label: LabelModel) {
 
 	for (const l in labels.value) {
 		if (labels.value[l].id === label.id) {
-			labels.value.splice(l, 1)
+			labels.value.splice(l, 1) // FIXME: l should be index
 		}
 	}
 	emit('update:modelValue', labels.value)
diff --git a/src/components/tasks/partials/listSearch.vue b/src/components/tasks/partials/listSearch.vue
index 58c156439..df53679f3 100644
--- a/src/components/tasks/partials/listSearch.vue
+++ b/src/components/tasks/partials/listSearch.vue
@@ -1,5 +1,5 @@
 <template>
-	<multiselect
+	<Multiselect
 		class="control is-expanded"
 		:placeholder="$t('list.search')"
 		@search="findLists"
@@ -13,7 +13,7 @@
 			<span class="list-namespace-title search-result">{{ namespace(props.option.namespaceId) }} ></span>
 			{{ props.option.title }}
 		</template>
-	</multiselect>
+	</Multiselect>
 </template>
 
 <script lang="ts" setup>
diff --git a/src/components/tasks/partials/reminders.vue b/src/components/tasks/partials/reminders.vue
index 45632c736..0f771aa42 100644
--- a/src/components/tasks/partials/reminders.vue
+++ b/src/components/tasks/partials/reminders.vue
@@ -45,8 +45,8 @@ const props = defineProps({
 				return false
 			}
 
-			const isDate = (e: any) => e instanceof Date
-			const isString = (e: any) => typeof e === 'string'
+			const isDate = (e: unknown) => e instanceof Date
+			const isString = (e: unknown) => typeof e === 'string'
 
 			for (const e of prop) {
 				if (!isDate(e) && !isString(e)) {
diff --git a/src/helpers/attachments.ts b/src/helpers/attachments.ts
index 4532bee12..e578fc220 100644
--- a/src/helpers/attachments.ts
+++ b/src/helpers/attachments.ts
@@ -29,6 +29,6 @@ export async function uploadFiles(attachmentService: AttachmentService, taskId:
 	}
 }
 
-export function generateAttachmentUrl(taskId: number, attachmentId: number) : any {
+export function generateAttachmentUrl(taskId: number, attachmentId: number) {
 	return `${window.API_URL}/tasks/${taskId}/attachments/${attachmentId}`
 }
\ No newline at end of file
diff --git a/src/helpers/utils.ts b/src/helpers/utils.ts
index c735aa658..c65f0ddb4 100644
--- a/src/helpers/utils.ts
+++ b/src/helpers/utils.ts
@@ -11,11 +11,11 @@ export function includesById(array: [], id: string | number) {
 }
 
 // https://github.com/you-dont-need/You-Dont-Need-Lodash-Underscore#_isnil
-export function isNil(value: any) {
+export function isNil(value: unknown) {
 	return value == null
 }
 
-export function omitBy(obj: {}, check: (value: any) => boolean): {} {
+export function omitBy(obj: {}, check: (value: unknown) => boolean) {
 	if (isNil(obj)) {
 		return {}
 	}
diff --git a/src/models/constants/priorities.ts b/src/models/constants/priorities.ts
index b3cf85cb3..598adfd98 100644
--- a/src/models/constants/priorities.ts
+++ b/src/models/constants/priorities.ts
@@ -5,4 +5,6 @@ export const PRIORITIES = {
 	'HIGH': 3,
 	'URGENT': 4,
 	'DO_NOW': 5,
-} as const
\ No newline at end of file
+} as const
+
+export type Priority = typeof PRIORITIES[keyof typeof PRIORITIES]
\ No newline at end of file
diff --git a/src/models/task.ts b/src/models/task.ts
index 540530db6..4ede946b1 100644
--- a/src/models/task.ts
+++ b/src/models/task.ts
@@ -6,6 +6,7 @@ import AttachmentModel from './attachment'
 import SubscriptionModel from '@/models/subscription'
 import {parseDateOrNull} from '@/helpers/parseDateOrNull'
 import type ListModel from './list'
+import type { Priority } from './constants/priorities'
 
 const SUPPORTS_TRIGGERED_NOTIFICATION = 'Notification' in window && 'showTrigger' in Notification.prototype
 export const TASK_DEFAULT_COLOR = '#1973ff'
@@ -29,7 +30,7 @@ export default class TaskModel extends AbstractModel {
 	description: string
 	done: boolean
 	doneAt: Date | null
-	priority: 0
+	priority: Priority
 	labels: LabelModel[]
 	assignees: UserModel[]
 
diff --git a/src/models/taskRelation.ts b/src/models/taskRelation.ts
index 5a944c027..66ffe485f 100644
--- a/src/models/taskRelation.ts
+++ b/src/models/taskRelation.ts
@@ -2,18 +2,20 @@ import AbstractModel from './abstractModel'
 import UserModel from './user'
 import type TaskModel from './task'
 
-export const RELATION_KINDS = [
-	'subtask',
-	'parenttask',
-	'related',
-	'duplicates',
-	'blocking',
-	'blocked',
-	'precedes',
-	'follows',
-	'copiedfrom',
-	'copiedto',
-  ] as const
+export const RELATION_KIND = {
+	'SUBTASK': 'subtask',
+	'PARENTTASK': 'parenttask',
+	'RELATED': 'related',
+	'DUPLICATES': 'duplicates',
+	'BLOCKING': 'blocking',
+	'BLOCKED': 'blocked',
+	'PROCEDES': 'precedes',
+	'FOLLOWS': 'follows',
+	'COPIEDFROM': 'copiedfrom',
+	'COPIEDTO': 'copiedto',
+ } as const
+
+export const RELATION_KINDS = [...Object.values(RELATION_KIND)] as const
 
 export type RelationKind = typeof RELATION_KINDS[number]
 
diff --git a/src/modules/parseTaskText.ts b/src/modules/parseTaskText.ts
index c3c8ad7d4..d30975b8d 100644
--- a/src/modules/parseTaskText.ts
+++ b/src/modules/parseTaskText.ts
@@ -47,7 +47,7 @@ interface repeatParsedResult {
 	repeats: Repeats | null,
 }
 
-interface ParsedTaskText {
+export interface ParsedTaskText {
 	text: string,
 	date: Date | null,
 	labels: string[],
diff --git a/src/services/abstractService.ts b/src/services/abstractService.ts
index 0b3002ce3..ba89178a3 100644
--- a/src/services/abstractService.ts
+++ b/src/services/abstractService.ts
@@ -2,6 +2,8 @@ import axios, {Method} from 'axios'
 import {objectToSnakeCase} from '@/helpers/case'
 import {getToken} from '@/helpers/auth'
 import AbstractModel from '@/models/abstractModel'
+import type { Right } from '@/models/constants/rights'
+import type FileModel from '@/models/file'
 
 interface Paths {
 	create : string
@@ -19,7 +21,7 @@ function convertObject(o: Record<string, unknown>) {
 	return o
 }
 
-function prepareParams(params: Record<string, unknown | any[]>) {
+function prepareParams(params: Record<string, unknown | unknown[]>) {
 	if (typeof params !== 'object') {
 		return params
 	}
@@ -36,7 +38,7 @@ function prepareParams(params: Record<string, unknown | any[]>) {
 	return objectToSnakeCase(params)
 }
 
-export default class AbstractService<Model extends AbstractModel> {
+export default class AbstractService<Model extends AbstractModel = AbstractModel> {
 
 	/////////////////////////////
 	// Initial variable definitions
@@ -133,8 +135,8 @@ export default class AbstractService<Model extends AbstractModel> {
 	/**
 	 * Returns an object with all route parameters and their values.
 	 */
-	getRouteReplacements(route : string, parameters = {}) {
-		const replace$$1: {} = {}
+	getRouteReplacements(route : string, parameters : Record<string, unknown> = {}) {
+		const replace$$1: Record<string, unknown> = {}
 		let pattern = this.getRouteParameterPattern()
 		pattern = new RegExp(pattern instanceof RegExp ? pattern.source : pattern, 'g')
 
@@ -170,7 +172,7 @@ export default class AbstractService<Model extends AbstractModel> {
 	 * But because the timeout is created using setTimeout, it will still trigger even if the request is
 	 * already finished, so we return a method to call in that case.
 	 */
-	setLoading(): Function {
+	setLoading() {
 		const timeout = setTimeout(() => {
 			this.loading = true
 		}, 100)
@@ -276,7 +278,7 @@ export default class AbstractService<Model extends AbstractModel> {
 	 * This is a more abstract implementation which only does a get request.
 	 * Services which need more flexibility can use this.
 	 */
-	async getM(url : string, model = new AbstractModel({}), params = {}) {
+	async getM(url : string, model = new AbstractModel({}) as Model, params: Record<string, unknown> = {}) {
 		const cancel = this.setLoading()
 
 		model = this.beforeGet(model)
@@ -285,7 +287,7 @@ export default class AbstractService<Model extends AbstractModel> {
 		try {
 			const response = await this.http.get(finalUrl, {params: prepareParams(params)})
 			const result = this.modelGetFactory(response.data)
-			result.maxRight = Number(response.headers['x-max-right'])
+			result.maxRight = Number(response.headers['x-max-right']) as Right
 			return result
 		} finally {
 			cancel()
@@ -309,7 +311,7 @@ export default class AbstractService<Model extends AbstractModel> {
 	 * @param params Optional query parameters
 	 * @param page The page to get
 	 */
-	async getAll(model : Model = new AbstractModel({}), params = {}, page = 1) {
+	async getAll(model : Model = new AbstractModel({}) as Model, params = {}, page = 1) {
 		if (this.paths.getAll === '') {
 			throw new Error('This model is not able to get data.')
 		}
@@ -415,10 +417,10 @@ export default class AbstractService<Model extends AbstractModel> {
 	/**
 	 * Uploads a file to a url.
 	 * @param url
-	 * @param file
+	 * @param file {FileModel}
 	 * @param fieldName The name of the field the file is uploaded to.
 	 */
-	uploadFile(url : string, file, fieldName : string) {
+	uploadFile(url : string, file: FileModel, fieldName : string) {
 		return this.uploadBlob(url, new Blob([file]), fieldName, file.name)
 	}
 
@@ -434,7 +436,7 @@ export default class AbstractService<Model extends AbstractModel> {
 	/**
 	 * Uploads a form data object.
 	 */
-	async uploadFormData(url : string, formData: Record<string, unknown>) {
+	async uploadFormData(url : string, formData: FormData) {
 		const cancel = this.setLoading()
 		try {
 			const response = await this.http.put(
diff --git a/src/services/attachment.ts b/src/services/attachment.ts
index 098d5ef6f..9422bd04e 100644
--- a/src/services/attachment.ts
+++ b/src/services/attachment.ts
@@ -2,8 +2,9 @@ import AbstractService from './abstractService'
 import AttachmentModel from '../models/attachment'
 import {formatISO} from 'date-fns'
 import {downloadBlob} from '@/helpers/downloadBlob'
+import type FileModel from '@/models/file'
 
-export default class AttachmentService extends AbstractService {
+export default class AttachmentService extends AbstractService<AttachmentModel> {
 	constructor() {
 		super({
 			create: '/tasks/{taskId}/attachments',
@@ -12,7 +13,7 @@ export default class AttachmentService extends AbstractService {
 		})
 	}
 
-	processModel(model) {
+	processModel(model: AttachmentModel) {
 		model.created = formatISO(new Date(model.created))
 		return model
 	}
@@ -33,26 +34,25 @@ export default class AttachmentService extends AbstractService {
 		return data
 	}
 
-	getBlobUrl(model) {
+	getBlobUrl(model: AttachmentModel) {
 		return AbstractService.prototype.getBlobUrl.call(this, '/tasks/' + model.taskId + '/attachments/' + model.id)
 	}
 
-	async download(model) {
+	async download(model: AttachmentModel) {
 		const url = await this.getBlobUrl(model)
 		return downloadBlob(url, model.file.name)
 	}
 
 	/**
 	 * Uploads a file to the server
-	 * @param model
 	 * @param files
 	 * @returns {Promise<any|never>}
 	 */
-	create(model, files) {
+	create(model: AttachmentModel, files: FileModel[]) {
 		const data = new FormData()
 		for (let i = 0; i < files.length; i++) {
 			// TODO: Validation of file size
-			data.append('files', new Blob([files[i]]), files[i].name)
+			data.append('files', new Blob([JSON.stringify(files[i], null, 2)]), files[i].name)
 		}
 
 		return this.uploadFormData(
diff --git a/src/services/backgroundUpload.ts b/src/services/backgroundUpload.ts
index 0f9d9792d..b961061d4 100644
--- a/src/services/backgroundUpload.ts
+++ b/src/services/backgroundUpload.ts
@@ -1,5 +1,6 @@
 import AbstractService from './abstractService'
 import ListModel from '../models/list'
+import type FileModel from '@/models/file'
 
 export default class BackgroundUploadService extends AbstractService {
 	constructor() {
@@ -18,11 +19,10 @@ export default class BackgroundUploadService extends AbstractService {
 
 	/**
 	 * Uploads a file to the server
-	 * @param listId
 	 * @param file
 	 * @returns {Promise<any|never>}
 	 */
-	create(listId: ListModel['id'], file) {
+	create(listId: ListModel['id'], file: FileModel) {
 		return this.uploadFile(
 			this.getReplacedRoute(this.paths.create, {listId}),
 			file,
diff --git a/src/services/task.ts b/src/services/task.ts
index c17bc2ef4..b8b69a418 100644
--- a/src/services/task.ts
+++ b/src/services/task.ts
@@ -113,7 +113,7 @@ export default class TaskService extends AbstractService {
 			model.labels = model.labels.map(l => labelService.processModel(l))
 		}
 
-		return model
+		return model as TaskModel
 	}
 }