diff --git a/src/lib/server/db/category.ts b/src/lib/server/db/category.ts
index fb85322..d710b34 100644
--- a/src/lib/server/db/category.ts
+++ b/src/lib/server/db/category.ts
@@ -2,7 +2,7 @@ import { IntegrityError } from "./error";
 import db from "./kysely";
 import type { Ciphertext } from "./schema";
 
-type CategoryId = "root" | number;
+export type CategoryId = "root" | number;
 
 interface Category {
   id: number;
diff --git a/src/lib/server/db/file.ts b/src/lib/server/db/file.ts
index 789c3b3..8b7819b 100644
--- a/src/lib/server/db/file.ts
+++ b/src/lib/server/db/file.ts
@@ -3,7 +3,7 @@ import { IntegrityError } from "./error";
 import db from "./kysely";
 import type { Ciphertext } from "./schema";
 
-type DirectoryId = "root" | number;
+export type DirectoryId = "root" | number;
 
 interface Directory {
   id: number;
diff --git a/src/lib/server/schemas/category.ts b/src/lib/server/schemas/category.ts
new file mode 100644
index 0000000..13032b3
--- /dev/null
+++ b/src/lib/server/schemas/category.ts
@@ -0,0 +1,28 @@
+import { z } from "zod";
+
+export const categoryIdSchema = z.union([z.enum(["root"]), z.number().int().positive()]);
+
+export const categoryInfoResponse = z.object({
+  metadata: z
+    .object({
+      parent: categoryIdSchema,
+      mekVersion: z.number().int().positive(),
+      dek: z.string().base64().nonempty(),
+      dekVersion: z.string().datetime(),
+      name: z.string().base64().nonempty(),
+      nameIv: z.string().base64().nonempty(),
+    })
+    .optional(),
+  subCategories: z.number().int().positive().array(),
+});
+export type CategoryInfoResponse = z.infer<typeof categoryInfoResponse>;
+
+export const categoryCreateRequest = z.object({
+  parent: categoryIdSchema,
+  mekVersion: z.number().int().positive(),
+  dek: z.string().base64().nonempty(),
+  dekVersion: z.string().datetime(),
+  name: z.string().base64().nonempty(),
+  nameIv: z.string().base64().nonempty(),
+});
+export type CategoryCreateRequest = z.infer<typeof categoryCreateRequest>;
diff --git a/src/lib/server/schemas/directory.ts b/src/lib/server/schemas/directory.ts
index 15a5886..473d696 100644
--- a/src/lib/server/schemas/directory.ts
+++ b/src/lib/server/schemas/directory.ts
@@ -1,9 +1,11 @@
 import { z } from "zod";
 
+export const directoryIdSchema = z.union([z.enum(["root"]), z.number().int().positive()]);
+
 export const directoryInfoResponse = z.object({
   metadata: z
     .object({
-      parent: z.union([z.enum(["root"]), z.number().int().positive()]),
+      parent: directoryIdSchema,
       mekVersion: z.number().int().positive(),
       dek: z.string().base64().nonempty(),
       dekVersion: z.string().datetime(),
@@ -29,7 +31,7 @@ export const directoryRenameRequest = z.object({
 export type DirectoryRenameRequest = z.infer<typeof directoryRenameRequest>;
 
 export const directoryCreateRequest = z.object({
-  parent: z.union([z.enum(["root"]), z.number().int().positive()]),
+  parent: directoryIdSchema,
   mekVersion: z.number().int().positive(),
   dek: z.string().base64().nonempty(),
   dekVersion: z.string().datetime(),
diff --git a/src/lib/server/schemas/file.ts b/src/lib/server/schemas/file.ts
index 781baf2..8f552f7 100644
--- a/src/lib/server/schemas/file.ts
+++ b/src/lib/server/schemas/file.ts
@@ -1,8 +1,9 @@
 import mime from "mime";
 import { z } from "zod";
+import { directoryIdSchema } from "./directory";
 
 export const fileInfoResponse = z.object({
-  parent: z.union([z.enum(["root"]), z.number().int().positive()]),
+  parent: directoryIdSchema,
   mekVersion: z.number().int().positive(),
   dek: z.string().base64().nonempty(),
   dekVersion: z.string().datetime(),
@@ -39,7 +40,7 @@ export const duplicateFileScanResponse = z.object({
 export type DuplicateFileScanResponse = z.infer<typeof duplicateFileScanResponse>;
 
 export const fileUploadRequest = z.object({
-  parent: z.union([z.enum(["root"]), z.number().int().positive()]),
+  parent: directoryIdSchema,
   mekVersion: z.number().int().positive(),
   dek: z.string().base64().nonempty(),
   dekVersion: z.string().datetime(),
diff --git a/src/lib/server/schemas/index.ts b/src/lib/server/schemas/index.ts
index 6f8270b..1fed0d0 100644
--- a/src/lib/server/schemas/index.ts
+++ b/src/lib/server/schemas/index.ts
@@ -1,4 +1,5 @@
 export * from "./auth";
+export * from "./category";
 export * from "./client";
 export * from "./directory";
 export * from "./file";
diff --git a/src/lib/server/services/category.ts b/src/lib/server/services/category.ts
new file mode 100644
index 0000000..5dd6c65
--- /dev/null
+++ b/src/lib/server/services/category.ts
@@ -0,0 +1,45 @@
+import { error } from "@sveltejs/kit";
+import {
+  registerCategory,
+  getAllCategoriesByParent,
+  getCategory,
+  type CategoryId,
+  type NewCategory,
+} from "$lib/server/db/category";
+import { IntegrityError } from "$lib/server/db/error";
+
+export const getCategoryInformation = async (userId: number, categoryId: CategoryId) => {
+  const category = categoryId !== "root" ? await getCategory(userId, categoryId) : undefined;
+  if (category === null) {
+    error(404, "Invalid category id");
+  }
+
+  const categories = await getAllCategoriesByParent(userId, categoryId);
+  return {
+    metadata: category && {
+      parentId: category.parentId ?? ("root" as const),
+      mekVersion: category.mekVersion,
+      encDek: category.encDek,
+      dekVersion: category.dekVersion,
+      encName: category.encName,
+    },
+    categories: categories.map(({ id }) => id),
+  };
+};
+
+export const createCategory = async (params: NewCategory) => {
+  const oneMinuteAgo = new Date(Date.now() - 60 * 1000);
+  const oneMinuteLater = new Date(Date.now() + 60 * 1000);
+  if (params.dekVersion <= oneMinuteAgo || params.dekVersion >= oneMinuteLater) {
+    error(400, "Invalid DEK version");
+  }
+
+  try {
+    await registerCategory(params);
+  } catch (e) {
+    if (e instanceof IntegrityError && e.message === "Inactive MEK version") {
+      error(400, "Inactive MEK version");
+    }
+    throw e;
+  }
+};
diff --git a/src/lib/server/services/directory.ts b/src/lib/server/services/directory.ts
index be795b0..2525069 100644
--- a/src/lib/server/services/directory.ts
+++ b/src/lib/server/services/directory.ts
@@ -8,11 +8,12 @@ import {
   setDirectoryEncName,
   unregisterDirectory,
   getAllFilesByParent,
+  type DirectoryId,
   type NewDirectory,
 } from "$lib/server/db/file";
 import type { Ciphertext } from "$lib/server/db/schema";
 
-export const getDirectoryInformation = async (userId: number, directoryId: "root" | number) => {
+export const getDirectoryInformation = async (userId: number, directoryId: DirectoryId) => {
   const directory = directoryId !== "root" ? await getDirectory(userId, directoryId) : undefined;
   if (directory === null) {
     error(404, "Invalid directory id");
diff --git a/src/routes/api/category/[id]/+server.ts b/src/routes/api/category/[id]/+server.ts
new file mode 100644
index 0000000..4a486fa
--- /dev/null
+++ b/src/routes/api/category/[id]/+server.ts
@@ -0,0 +1,33 @@
+import { error, json } from "@sveltejs/kit";
+import { z } from "zod";
+import { authorize } from "$lib/server/modules/auth";
+import { categoryInfoResponse, type CategoryInfoResponse } from "$lib/server/schemas";
+import { getCategoryInformation } from "$lib/server/services/category";
+import type { RequestHandler } from "./$types";
+
+export const GET: RequestHandler = async ({ locals, params }) => {
+  const { userId } = await authorize(locals, "activeClient");
+
+  const zodRes = z
+    .object({
+      id: z.union([z.enum(["root"]), z.coerce.number().int().positive()]),
+    })
+    .safeParse(params);
+  if (!zodRes.success) error(400, "Invalid path parameters");
+  const { id } = zodRes.data;
+
+  const { metadata, categories } = await getCategoryInformation(userId, id);
+  return json(
+    categoryInfoResponse.parse({
+      metadata: metadata && {
+        parent: metadata.parentId,
+        mekVersion: metadata.mekVersion,
+        dek: metadata.encDek,
+        dekVersion: metadata.dekVersion.toISOString(),
+        name: metadata.encName.ciphertext,
+        nameIv: metadata.encName.iv,
+      },
+      subCategories: categories,
+    } satisfies CategoryInfoResponse),
+  );
+};
diff --git a/src/routes/api/category/create/+server.ts b/src/routes/api/category/create/+server.ts
new file mode 100644
index 0000000..216d850
--- /dev/null
+++ b/src/routes/api/category/create/+server.ts
@@ -0,0 +1,23 @@
+import { error, text } from "@sveltejs/kit";
+import { authorize } from "$lib/server/modules/auth";
+import { categoryCreateRequest } from "$lib/server/schemas";
+import { createCategory } from "$lib/server/services/category";
+import type { RequestHandler } from "./$types";
+
+export const POST: RequestHandler = async ({ locals, request }) => {
+  const { userId } = await authorize(locals, "activeClient");
+
+  const zodRes = categoryCreateRequest.safeParse(await request.json());
+  if (!zodRes.success) error(400, "Invalid request body");
+  const { parent, mekVersion, dek, dekVersion, name, nameIv } = zodRes.data;
+
+  await createCategory({
+    userId,
+    parentId: parent,
+    mekVersion,
+    encDek: dek,
+    dekVersion: new Date(dekVersion),
+    encName: { ciphertext: name, iv: nameIv },
+  });
+  return text("Category created", { headers: { "Content-Type": "text/plain" } });
+};