diff --git a/package-lock.json b/package-lock.json
index 1bfaa7f..4c20db1 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -1,12 +1,12 @@
 {
   "name": "t4.ts",
-  "version": "0.0.4",
+  "version": "0.0.21",
   "lockfileVersion": 3,
   "requires": true,
   "packages": {
     "": {
       "name": "t4.ts",
-      "version": "0.0.4",
+      "version": "0.0.21",
       "license": "MIT",
       "dependencies": {
         "typedoc-plugin-missing-exports": "^2.1.0"
diff --git a/package.json b/package.json
index 7d19e11..8c656a6 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "t4.ts",
-  "version": "0.0.21",
+  "version": "0.0.22",
   "description": "TypeScript API Library for TerminalFour",
   "type": "module",
   "exports": {
@@ -19,7 +19,7 @@
   "module": "./mjs/index.js",
   "scripts": {
     "build": "npx tsc --module es2022 --outDir esm/ && npx tsc --module commonjs --outDir cjs/",
-    "docs":  "npx typedoc src/index.ts --plugin typedoc-plugin-missing-exports --excludeExternals true"
+    "docs": "npx typedoc src/index.ts --plugin typedoc-plugin-missing-exports --excludeExternals true"
   },
   "repository": {
     "type": "git",
diff --git a/src/lib/Client.ts b/src/lib/Client.ts
index 4194086..3108afe 100644
--- a/src/lib/Client.ts
+++ b/src/lib/Client.ts
@@ -16,6 +16,8 @@ import { Version } from "./Version.js"
 export class Client {
   url: String
   private token: String
+  language: string
+  fetch: any
 
   content: Content
   contentType: ContentType
@@ -25,13 +27,12 @@ export class Client {
   media: Media
   mediaCategory: MediaCategory
   mediaType: MediaType
-  language: string
   list: List
   profile: Profile
   serverSideLink: ServerSideLink
   upload: Upload
   version: Version
-  constructor(url: string, token: string, language: string = 'en') {
+  constructor(url: string, token: string, language: string = 'en', _fetch = fetch) {
     this.url = url
     this.token = token
     this.language = language
@@ -51,6 +52,7 @@ export class Client {
     this.version = new Version(this)
 
     this.isAuthorized = this.isAuthorized.bind(this)
+    this.fetch = _fetch
   }
   
   async call(method: string, endpoint: string, options: any) {
@@ -66,7 +68,7 @@ export class Client {
         headers['content-type'] = 'application/json'
       }
       headers = options?.headers ? Object.assign(options.headers, headers) : headers
-      const request = await fetch(`${this.url}/${endpoint}`, {
+      const request = await this.fetch(`${this.url}/${endpoint}`, {
         ...options,
         headers,
         method,
diff --git a/src/lib/Content.ts b/src/lib/Content.ts
index 66f50e9..994982d 100644
--- a/src/lib/Content.ts
+++ b/src/lib/Content.ts
@@ -66,7 +66,7 @@ export class Content {
     return await response.json()
   }
 
-  async delete(contentId: number, sectionId: number, language: string = this.client.language) {
+  async delete(contentId: number, sectionId: number, language: string = this.client.language): Promise<boolean> {
     const response = await this.client.call('DELETE', `${ContentEndpoint}/${sectionId}/${contentId}/${language}`, null)
     return response?.ok 
   }
diff --git a/src/lib/Hierarchy.ts b/src/lib/Hierarchy.ts
index eebaa01..c1661e3 100644
--- a/src/lib/Hierarchy.ts
+++ b/src/lib/Hierarchy.ts
@@ -52,12 +52,12 @@ export class Hierarchy {
     return await response.json()
   }
 
-  async delete(id: number, isMandatory?: boolean) {
+  async delete(id: number, isMandatory?: boolean): Promise<boolean> {
     const response = await this.client.call('DELETE', `${HierarchyEndpoint}/${id}${isMandatory ? '?mandatory=true' : ''}`, null)
     return response?.ok
   }
 
-  async update(id: number, options: Partial<SectionDTO>, language: string = this.client.language) {
+  async update(id: number, options: Partial<SectionDTO>, language: string = this.client.language): Promise<boolean> {
     let section = await this.get(id, language)
     const response = await this.client.call('PUT', `${HierarchyEndpoint}/${id}/${language}`, { body: Object.assign({}, section, options) })
     return response?.ok
diff --git a/src/lib/List.ts b/src/lib/List.ts
index d2cd268..2e0cb34 100644
--- a/src/lib/List.ts
+++ b/src/lib/List.ts
@@ -13,7 +13,7 @@ export class List {
     return await response.json()
   }
 
-  async modify(list: PredefinedListDTO, language: string = this.client.language): Promise<any> {
+  async modify(list: PredefinedListDTO, language: string = this.client.language): Promise<PredefinedListDTO> {
     // Assuming the list object was retrieved from the API, it will have a primaryGroup object name, fullAccess, and group.
     // The API expects the primaryGroup object to only have an id property and will fail if the other properties are present.
     if (Object.keys(list.primaryGroup).length > 1) list.primaryGroup = { id: list.primaryGroup.id }
diff --git a/src/lib/Media.ts b/src/lib/Media.ts
index 606ecff..c1591fe 100644
--- a/src/lib/Media.ts
+++ b/src/lib/Media.ts
@@ -1,5 +1,5 @@
 import { Client } from './Client.js'
-import { MediaCategoryObject, MediaData, MediaItemTableData, MediaRow, MediaUpload, MediaUploadData } from './utility/Global.js'
+import { MediaCategoryObject, MediaData, MediaItemDTO, MediaItemTableData, MediaRow, MediaUsageDTO, MediaUpload, MediaUploadData } from './utility/Global.js'
 import { batcher } from './utility/helpers.js'
 import * as path from 'path'
 import { readFile, stat } from 'fs/promises'
@@ -11,7 +11,7 @@ export class Media {
   constructor(client:Client) {
     this.client = client
     this.util = {
-      getMediaIDs: async (parentID: number, arrLimit: number = 50, reqTimeout: number = 10000) => {
+      getMediaIDs: async (parentID: number, arrLimit: number = 50, reqTimeout: number = 10000): Promise<number[]> => {
         const structure = await this.client.mediaCategory.list(parentID, 'en')
         let categoryIds: number[] = []
         const populateIds = (category: MediaCategoryObject) => {
@@ -39,18 +39,18 @@ export class Media {
     return await response.json()
   }
 
-  async get(contentId: number, language: string = this.client.language) {
+  async get(contentId: number, language: string = this.client.language): Promise<MediaItemDTO> {
     const response = await this.client.call('GET', `${MediaEndpoint}/${contentId}/${language}`, null)
     return await response.json()
   }
 
-  async getMediaUsage(mediaID: number, language: string = this.client.language) {
+  async getMediaUsage(mediaID: number, language: string = this.client.language): Promise<MediaUsageDTO[]> {
     const response = await this.client.call('GET', `${MediaEndpoint}/${mediaID}/${language}/usage`, null)
     return await response.json()
   }
 
-  async bulkGetMediaUsage (mediaIDs: number[], language: string = this.client.language) {
-    const response = await this.client.call('POST', `${MediaEndpoint}/getUsage/${language}`, {body: mediaIDs})
+  async bulkGetMediaUsage(mediaIDs: number[], language: string = this.client.language) {
+    const response = await this.client.call('POST', `${MediaEndpoint}/getUsage/${language}`, { body: mediaIDs })
     return await response.json()
   }
 
@@ -64,7 +64,7 @@ export class Media {
     return await response.json()
   }
 
-  async downloadSingle(id: number, type: 'media' | 'file' | 'thumbnail', version?: string) {
+  async downloadSingle(id: number, type: 'media' | 'file' | 'thumbnail', version?: string): Promise<ArrayBuffer | null> {
     if (!version) version = (await this.client.content.getVersions(id, 'smxx'))[0].version
     const inital = await this.client.call('GET', `${MediaEndpoint}/${id}/smxx/${version}/${type}`, { redirect: 'manual' })
     if (inital.status != 302) return null
diff --git a/src/lib/utility/Global.ts b/src/lib/utility/Global.ts
index 309e92a..1860666 100644
--- a/src/lib/utility/Global.ts
+++ b/src/lib/utility/Global.ts
@@ -294,6 +294,41 @@ export interface MediaItemTableData {
   mediaRows:       MediaRow[];
 }
 
+export interface MediaItemDTO {
+  id: number
+  contentTypeID: number
+  archiveSection: number
+  language: string
+  name: string
+  status: number
+  lastModifiedBy: number
+  version: string
+  editable: boolean
+  expired: boolean
+  canPublishNow: boolean
+  canSaveAndApprove: boolean
+  contentTypeAccess: number
+  elements: Elements
+  contentType: ContentTypeDTO
+  types: Type[]
+  syntax: number
+  type: number
+  binaryLanguage: string
+  categories: number[]
+  description: string
+  typeName: string
+  mediaURL: string
+  thumbnailURL: string
+  mediaPath: string
+  mediaSize: number
+  fileName: string
+  variant: number
+  variantName: string
+  variantDimensions: string
+  accessLevel: number
+  mediaCanHaveVariants: boolean
+}
+
 export interface MediaRow {
   id:               string;
   status:           string;
@@ -556,6 +591,21 @@ export interface FormUsageDTO {
   name: string
 }
 
+export interface MediaUsageDTO {
+  contentName: string
+  assetType: string
+  variant: string
+  location: string
+  occurrences: number
+  language: string
+  contentID: number
+  sectionID: number
+  hasAccess: boolean
+  contentLayoutContentTypeID: number
+  mediaID: number
+  variantUsage: boolean
+}
+
 export interface contenUploadDTO {
   id?: number
   channels?: number[]