diff --git a/ccm-apiclient-commons/src/main/typescript/entities.ts b/ccm-apiclient-commons/src/main/typescript/entities.ts
index e341e94ce..e9ab8468f 100644
--- a/ccm-apiclient-commons/src/main/typescript/entities.ts
+++ b/ccm-apiclient-commons/src/main/typescript/entities.ts
@@ -1,3 +1,25 @@
+/**
+ * A list view contains an array of objects and some data about the list.
+ */
+export interface ListView<T> {
+    /**
+     * The list of objects
+     */
+    list: T[],
+    /**
+     * The number of elements for the query.
+     */
+    count: number,
+    /**
+     * Items per page
+     */
+    limit: number,
+    /**
+     * The first item shown
+     */
+    offset: number,
+}
+
 /**
  * Properties of the type `LocalizedString` are used in several entities
  * returned by various of the endpoints the RESTful API of LibreCCM.
@@ -7,3 +29,4 @@
 export interface LocalizedString {
     values: Record<string, string>
 }
+
diff --git a/ccm-core-apiclient/src/main/typescript/clients/categorization-api.ts b/ccm-core-apiclient/src/main/typescript/clients/categorization-api.ts
index 1d4138324..48642434d 100644
--- a/ccm-core-apiclient/src/main/typescript/clients/categorization-api.ts
+++ b/ccm-core-apiclient/src/main/typescript/clients/categorization-api.ts
@@ -1,9 +1,15 @@
 import {
     ApiResponse,
     LibreCcmApiClient,
+    ListView,
 } from "@libreccm/ccm-apiclient-commons";
 
-import { Category, buildCategoryFromRecord } from "../entities/categorization";
+import {
+    Category,
+    Categorization,
+    buildCategoryFromRecord,
+    buildCategorizationFromRecord,
+} from "../entities/categorization";
 import * as Constants from "../constants";
 
 export class CategorizationApiClient {
@@ -69,7 +75,7 @@ export class CategorizationApiClient {
         }
     }
 
-    async updateCategoryByDomainAndPath(
+    async updateCategoryOfDomain(
         domain: string,
         path: string,
         category: Category
@@ -91,7 +97,7 @@ export class CategorizationApiClient {
         }
     }
 
-    async updateCategoryById(
+    async updateCategoryWithId(
         categoryId: number,
         category: Category
     ): Promise<void> {
@@ -112,7 +118,7 @@ export class CategorizationApiClient {
         }
     }
 
-    async updateCategoryByUuid(
+    async updateCategoryWithUuid(
         uuid: string,
         category: Category
     ): Promise<void> {
@@ -133,10 +139,7 @@ export class CategorizationApiClient {
         }
     }
 
-    async deleteCategoryByDomainAndPath(
-        domain: string,
-        path: string
-    ): Promise<void> {
+    async deleteCategoryOfDomain(domain: string, path: string): Promise<void> {
         try {
             const response: ApiResponse = await this.#apiClient.delete(
                 `${this.#CATEGORIES_API_PREFIX}/${domain}/${path}`
@@ -148,12 +151,12 @@ export class CategorizationApiClient {
                 throw `Failed to update category ${path} of domain ${domain}:
                 ${response.status} ${response.statusText}`;
             }
-        } catch(err) {
+        } catch (err) {
             throw `Failed to delete category ${path} of domain ${domain}: ${err}`;
         }
     }
 
-    async deleteCategoryById(categoryId: number): Promise<void> {
+    async deleteCategoryWithId(categoryId: number): Promise<void> {
         try {
             const response: ApiResponse = await this.#apiClient.delete(
                 `${this.#CATEGORIES_API_PREFIX}/ID-${categoryId}`
@@ -170,12 +173,10 @@ export class CategorizationApiClient {
         }
     }
 
-    async deleteCategoryByUuid(
-        uuid: string,
-    ): Promise<void> {
+    async deleteCategoryWithUuid(uuid: string): Promise<void> {
         try {
             const response: ApiResponse = await this.#apiClient.delete(
-                `${this.#CATEGORIES_API_PREFIX}/UUID-${uuid}`,
+                `${this.#CATEGORIES_API_PREFIX}/UUID-${uuid}`
             );
 
             if (response.ok) {
@@ -188,4 +189,238 @@ export class CategorizationApiClient {
             throw `Failed to delete category with UUID ${uuid}: ${err}`;
         }
     }
+
+    async getSubCategoriesByDomainAndPath(
+        domain: string,
+        path: string,
+        limit = 20,
+        offset = 0
+    ): Promise<ListView<Category>> {
+        try {
+            const response: ApiResponse = await this.#apiClient.get(
+                `${
+                    this.#CATEGORIES_API_PREFIX
+                }/${domain}/${path}?limit=${limit}&offset=${offset}`
+            );
+
+            if (response.ok) {
+                const result: Record<string, unknown> = await response.json();
+                const list: Record<string, unknown>[] = result.list as Record<
+                    string,
+                    unknown
+                >[];
+                const categories: Category[] = list.map((record) =>
+                    buildCategoryFromRecord(record)
+                );
+
+                return {
+                    list: categories,
+                    count: result.count as number,
+                    limit: result.limit as number,
+                    offset: result.offset as number,
+                };
+            } else {
+                throw `Failed to get subcategories of category  ${path} of 
+                domain ${domain}:  ${response.status} ${response.statusText}`;
+            }
+        } catch (err) {
+            throw `Failed to get subcategories of category ${path} of 
+            domain ${domain}: ${err}`;
+        }
+    }
+
+    async getSubCategoriesById(
+        categoryId: number,
+        limit = 20,
+        offset = 0
+    ): Promise<ListView<Category>> {
+        try {
+            const response: ApiResponse = await this.#apiClient.get(
+                `${
+                    this.#CATEGORIES_API_PREFIX
+                }/ID-${categoryId}?limit=${limit}&offset=${offset}`
+            );
+
+            if (response.ok) {
+                const result: Record<string, unknown> = await response.json();
+                const list: Record<string, unknown>[] = result.list as Record<
+                    string,
+                    unknown
+                >[];
+                const categories: Category[] = list.map((record) =>
+                    buildCategoryFromRecord(record)
+                );
+
+                return {
+                    list: categories,
+                    count: result.count as number,
+                    limit: result.limit as number,
+                    offset: result.offset as number,
+                };
+            } else {
+                throw `Failed to get subcategories of category  with ID 
+                ${categoryId}:  ${response.status} ${response.statusText}`;
+            }
+        } catch (err) {
+            throw `Failed to get subcategories of category with 
+            ID ${categoryId}: ${err}`;
+        }
+    }
+
+    async getSubCategoriesByUuid(
+        uuid: string,
+        limit = 20,
+        offset = 0
+    ): Promise<ListView<Category>> {
+        try {
+            const response: ApiResponse = await this.#apiClient.get(
+                `${
+                    this.#CATEGORIES_API_PREFIX
+                }/UUID-${uuid}?limit=${limit}&offset=${offset}`
+            );
+
+            if (response.ok) {
+                const result: Record<string, unknown> = await response.json();
+                const list: Record<string, unknown>[] = result.list as Record<
+                    string,
+                    unknown
+                >[];
+                const categories: Category[] = list.map((record) =>
+                    buildCategoryFromRecord(record)
+                );
+
+                return {
+                    list: categories,
+                    count: result.count as number,
+                    limit: result.limit as number,
+                    offset: result.offset as number,
+                };
+            } else {
+                throw `Failed to get subcategories of category  with UUID 
+                ${uuid}:  ${response.status} ${response.statusText}`;
+            }
+        } catch (err) {
+            throw `Failed to get subcategories of category with 
+            UUID ${uuid}: ${err}`;
+        }
+    }
+
+    /**
+     * Add a new subcategory to category
+     *
+     * @param domain
+     * @param path
+     * @param category
+     *
+     * @returns A Promise which resolves to the full path (including domain)
+     * of the new subcategory.
+     */
+    async addSubCategoryToCategoryOfDomain(
+        domain: string,
+        path: string,
+        category: Category
+    ): Promise<string> {
+        try {
+            const response: ApiResponse = await this.#apiClient.post(
+                `${this.#CATEGORIES_API_PREFIX}/${domain}/${path}`,
+                JSON.stringify(category)
+            );
+
+            if (response.ok) {
+                const result: string = await response.text();
+                return result;
+            } else {
+                throw `Failed to add new subcategory to category ${path} of 
+                domain ${domain}: ${response.status} ${response.statusText}`;
+            }
+        } catch (err) {
+            throw `Failed to add new subcategory to category ${path} of 
+            domain ${domain}: ${err}`;
+        }
+    }
+
+    async addSubCategoryToWithId(
+        categoryId: number,
+        category: Category
+    ): Promise<string> {
+        try {
+            const response: ApiResponse = await this.#apiClient.post(
+                `${this.#CATEGORIES_API_PREFIX}/ID-${categoryId}`,
+                JSON.stringify(category)
+            );
+
+            if (response.ok) {
+                const result: string = await response.text();
+                return result;
+            } else {
+                throw `Failed to add new subcategory to category with 
+                ID ${categoryId}: ${response.status} ${response.statusText}`;
+            }
+        } catch (err) {
+            throw `Failed to add new subcategory to category with 
+            ID ${categoryId}: ${err}`;
+        }
+    }
+
+    async addSubCategoryToWithUuid(
+        uuid: string,
+        category: Category
+    ): Promise<string> {
+        try {
+            const response: ApiResponse = await this.#apiClient.post(
+                `${this.#CATEGORIES_API_PREFIX}/UUID-${uuid}`,
+                JSON.stringify(category)
+            );
+
+            if (response.ok) {
+                const result: string = await response.text();
+                return result;
+            } else {
+                throw `Failed to add new subcategory to category with 
+                UUID ${uuid}: ${response.status} ${response.statusText}`;
+            }
+        } catch (err) {
+            throw `Failed to add new subcategory to category with 
+            UUID ${uuid}: ${err}`;
+        }
+    }
+
+    async getObjectsInCategoryOfDomain(
+        domain: string,
+        path: string,
+        limit = 20,
+        offset = 0
+    ): Promise<ListView<Categorization>> {
+        try {
+            const response: ApiResponse = await this.#apiClient.get(
+                `${
+                    this.#CATEGORIES_API_PREFIX
+                }/$domain/${path}/objects?limit=${limit}&offset=${offset}`
+            );
+
+            if (response.ok) {
+                const result: Record<string, unknown> = await response.json();
+                const list: Record<string, unknown>[] = result.list as Record<
+                    string,
+                    unknown
+                >[];
+                const objects: Categorization[] = list.map((record) =>
+                    buildCategorizationFromRecord(record)
+                );
+
+                return {
+                    list: objects,
+                    count: result.count as number,
+                    limit: result.limit as number,
+                    offset: result.offset as number
+                }
+            } else {
+                throw `Failed to get objects in category ${path} of 
+                domain ${domain}:  ${response.status} ${response.statusText}`;
+            }
+        } catch (err) {
+            throw `Failed to get objects in category ${path} of 
+            domain ${domain}: ${err}`;
+        }
+    }
 }
diff --git a/ccm-core-apiclient/src/main/typescript/entities/categorization.ts b/ccm-core-apiclient/src/main/typescript/entities/categorization.ts
index 8660dcbaa..5590810a6 100644
--- a/ccm-core-apiclient/src/main/typescript/entities/categorization.ts
+++ b/ccm-core-apiclient/src/main/typescript/entities/categorization.ts
@@ -2,6 +2,7 @@ import {
     LocalizedString,
     assertProperties,
 } from "@libreccm/ccm-apiclient-commons";
+import { CcmObjectId } from "./core";
 
 export interface AssociatedCategory {
     name: string;
@@ -22,6 +23,16 @@ export interface Category {
     categoryOrder: number;
 }
 
+export interface Categorization {
+    categorizationId: number;
+    uuid: string;
+    categorizedObject: CcmObjectId;
+    indexObject: boolean;
+    categoryOrder: number;
+    objectOrder: number;
+    type: string;
+}
+
 export function buildCategoryFromRecord(
     record: Record<string, unknown>
 ): Category {
@@ -55,3 +66,27 @@ export function buildCategoryFromRecord(
         categoryOrder: record.categoryOrder as number,
     };
 }
+
+export function buildCategorizationFromRecord(
+    record: Record<string, unknown>
+): Categorization {
+    assertProperties(record, [
+        "categorizationId",
+        "uuid",
+        "categorizedObject",
+        "indexObject",
+        "categoryOrder",
+        "objectOrder",
+        "type"
+    ]);
+
+    return {
+        categorizationId: record.categorizationId as number,
+        uuid: record.uuid as string,
+        categorizedObject: record.categorizedObject as CcmObjectId,
+        indexObject: record.indexObject as boolean,
+        categoryOrder: record.categoryOrder as number,
+        objectOrder: record.objectOrder as number,
+        type: record.type as string
+    }
+}
diff --git a/ccm-core-apiclient/src/main/typescript/entities/core.ts b/ccm-core-apiclient/src/main/typescript/entities/core.ts
new file mode 100644
index 000000000..a75770a1e
--- /dev/null
+++ b/ccm-core-apiclient/src/main/typescript/entities/core.ts
@@ -0,0 +1,8 @@
+/**
+ * Basic data about an `CcmObject`.
+ */
+export interface CcmObjectId {
+    objectId: number,
+    uuid: string,
+    displayName: string
+}
\ No newline at end of file
diff --git a/ccm-core/src/site/resources/ccm-core-api.json b/ccm-core/src/site/resources/ccm-core-api.json
index baf747b89..9fffbe483 100644
--- a/ccm-core/src/site/resources/ccm-core-api.json
+++ b/ccm-core/src/site/resources/ccm-core-api.json
@@ -266,7 +266,7 @@
           "schema" : {
             "type" : "integer",
             "format" : "int32",
-            "default" : 20
+            "default" : 0
           }
         } ],
         "responses" : {
@@ -333,14 +333,16 @@
           "in" : "query",
           "schema" : {
             "type" : "integer",
-            "format" : "int32"
+            "format" : "int32",
+            "default" : 20
           }
         }, {
           "name" : "offset",
           "in" : "query",
           "schema" : {
             "type" : "integer",
-            "format" : "int32"
+            "format" : "int32",
+            "default" : 0
           }
         } ],
         "responses" : {
@@ -379,14 +381,16 @@
           "in" : "query",
           "schema" : {
             "type" : "integer",
-            "format" : "int32"
+            "format" : "int32",
+            "default" : 20
           }
         }, {
           "name" : "offset",
           "in" : "query",
           "schema" : {
             "type" : "integer",
-            "format" : "int32"
+            "format" : "int32",
+            "default" : 0
           }
         } ],
         "responses" : {
@@ -454,14 +458,16 @@
           "in" : "query",
           "schema" : {
             "type" : "integer",
-            "format" : "int32"
+            "format" : "int32",
+            "default" : 20
           }
         }, {
           "name" : "offset",
           "in" : "query",
           "schema" : {
             "type" : "integer",
-            "format" : "int32"
+            "format" : "int32",
+            "default" : 0
           }
         } ],
         "responses" : {
@@ -601,9 +607,9 @@
         }
       }
     },
-    "/api/admin/categories/UUID-{categoryId}/objects/objectIdentifier" : {
+    "/api/admin/categories/UUID-{categoryId}/objects/{objectIdentifier}" : {
       "delete" : {
-        "operationId" : "removeObjectsFromCategory",
+        "operationId" : "removeObjectFromCategory_2",
         "parameters" : [ {
           "name" : "categoryId",
           "in" : "path",
@@ -678,7 +684,7 @@
           "schema" : {
             "type" : "integer",
             "format" : "int32",
-            "default" : 20
+            "default" : 0
           }
         } ],
         "responses" : {
@@ -720,7 +726,7 @@
           "schema" : {
             "type" : "integer",
             "format" : "int32",
-            "default" : 20
+            "default" : 0
           }
         } ],
         "responses" : {