diff --git a/src/action/index.ts b/src/action/index.ts
index def6420..0098b6b 100644
--- a/src/action/index.ts
+++ b/src/action/index.ts
@@ -55,6 +55,7 @@ export { UpdateAppActivitiesAction } from './updateappactivities'
 export { UpdateCategoryBatteryLimitAction } from './updatecategorybatterylimit'
 export { UpdateCategoryBlockAllNotificationsAction } from './updatecategoryblockallnotifications'
 export { UpdateCategoryBlockedTimesAction } from './updatecategoryblockedtimes'
+export { UpdateCategorySortingAction } from './updatecategorysorting'
 export { UpdateCategoryTemporarilyBlockedAction } from './updatecategorytemporarilyblocked'
 export { UpdateCategoryTimeWarningsAction } from './updatecategorytimewarnings'
 export { UpdateCategoryTitleAction } from './updatecategorytitle'
diff --git a/src/action/serialization/parentaction.ts b/src/action/serialization/parentaction.ts
index dbd9f53..e0d5da0 100644
--- a/src/action/serialization/parentaction.ts
+++ b/src/action/serialization/parentaction.ts
@@ -45,6 +45,7 @@ import { SerializedSetUserTimezoneAction, SetUserTimezoneAction } from '../setus
 import { SerializedUpdateCategoryBatteryLimitAction, UpdateCategoryBatteryLimitAction } from '../updatecategorybatterylimit'
 import { SerializedUpdateCategoryBlockAllNotificationsAction, UpdateCategoryBlockAllNotificationsAction } from '../updatecategoryblockallnotifications'
 import { SerializedUpdateCategoryBlockedTimesAction, UpdateCategoryBlockedTimesAction } from '../updatecategoryblockedtimes'
+import { SerializedUpdateCategorySortingAction, UpdateCategorySortingAction } from '../updatecategorysorting'
 import { SerializedUpdateCategoryTemporarilyBlockedAction, UpdateCategoryTemporarilyBlockedAction } from '../updatecategorytemporarilyblocked'
 import { SerializedUpdateCategoryTimeWarningsAction, UpdateCategoryTimeWarningsAction } from '../updatecategorytimewarnings'
 import { SerializedUpdateCategoryTitleAction, UpdateCategoryTitleAction } from '../updatecategorytitle'
@@ -85,6 +86,7 @@ export type SerializedParentAction =
   SerializedUpdateCategoryBatteryLimitAction |
   SerializedUpdateCategoryBlockAllNotificationsAction |
   SerializedUpdateCategoryBlockedTimesAction |
+  SerializedUpdateCategorySortingAction |
   SerializedUpdateCategoryTemporarilyBlockedAction |
   SerializedUpdateCategoryTimeWarningsAction |
   SerializedUpdateCategoryTitleAction |
@@ -154,6 +156,8 @@ export const parseParentAction = (action: SerializedParentAction): ParentAction
     return UpdateCategoryBlockAllNotificationsAction.parse(action)
   } else if (action.type === 'UPDATE_CATEGORY_BLOCKED_TIMES') {
     return UpdateCategoryBlockedTimesAction.parse(action)
+  } else if (action.type === 'UPDATE_CATEGORY_SORTING') {
+    return UpdateCategorySortingAction.parse(action)
   } else if (action.type === 'UPDATE_CATEGORY_TIME_WARNINGS') {
     return UpdateCategoryTimeWarningsAction.parse(action)
   } else if (action.type === 'UPDATE_CATEGORY_TITLE') {
diff --git a/src/action/updatecategorysorting.ts b/src/action/updatecategorysorting.ts
new file mode 100644
index 0000000..3b58b48
--- /dev/null
+++ b/src/action/updatecategorysorting.ts
@@ -0,0 +1,56 @@
+/*
+ * server component for the TimeLimit App
+ * Copyright (C) 2019 - 2020 Jonas Lochmann
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as
+ * published by the Free Software Foundation, version 3 of the License.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+import { uniq } from 'lodash'
+import { assertIdWithinFamily } from '../util/token'
+import { ParentAction } from './basetypes'
+
+export class UpdateCategorySortingAction extends ParentAction {
+  readonly categoryIds: Array<string>
+
+  constructor ({ categoryIds }: {
+    categoryIds: Array<string>
+  }) {
+    super()
+
+    if (categoryIds.length === 0) {
+      throw new Error('empty category sorting list')
+    }
+
+    if (uniq(categoryIds).length !== categoryIds.length) {
+      throw new Error('category sorting list has duplicates')
+    }
+
+    categoryIds.forEach((categoryId) => assertIdWithinFamily(categoryId))
+
+    this.categoryIds = categoryIds
+  }
+
+  serialize = (): SerializedUpdateCategorySortingAction => ({
+    type: 'UPDATE_CATEGORY_SORTING',
+    categoryIds: this.categoryIds
+  })
+
+  static parse = ({ categoryIds }: SerializedUpdateCategorySortingAction) => (
+    new UpdateCategorySortingAction({ categoryIds })
+  )
+}
+
+export interface SerializedUpdateCategorySortingAction {
+  type: 'UPDATE_CATEGORY_SORTING'
+  categoryIds: Array<string>
+}
diff --git a/src/api/validator.ts b/src/api/validator.ts
index d2d1386..d15823b 100644
--- a/src/api/validator.ts
+++ b/src/api/validator.ts
@@ -839,6 +839,28 @@ const definitions = {
       "type"
     ]
   },
+  "SerializedUpdateCategorySortingAction": {
+    "type": "object",
+    "properties": {
+      "type": {
+        "type": "string",
+        "enum": [
+          "UPDATE_CATEGORY_SORTING"
+        ]
+      },
+      "categoryIds": {
+        "type": "array",
+        "items": {
+          "type": "string"
+        }
+      }
+    },
+    "additionalProperties": false,
+    "required": [
+      "categoryIds",
+      "type"
+    ]
+  },
   "SerializedUpdateCategoryTemporarilyBlockedAction": {
     "type": "object",
     "properties": {
@@ -1699,6 +1721,9 @@ export const isSerializedParentAction: (value: object) => value is SerializedPar
     {
       "$ref": "#/definitions/SerializedUpdateCategoryBlockedTimesAction"
     },
+    {
+      "$ref": "#/definitions/SerializedUpdateCategorySortingAction"
+    },
     {
       "$ref": "#/definitions/SerializedUpdateCategoryTemporarilyBlockedAction"
     },
diff --git a/src/database/category.ts b/src/database/category.ts
index 504de2f..eef1c70 100644
--- a/src/database/category.ts
+++ b/src/database/category.ts
@@ -57,9 +57,13 @@ export interface CategoryAttributesVersion6 {
   temporarilyBlockedEndTime: number
 }
 
+export interface CategoryAttributesVersion7 {
+  sort: number
+}
+
 export type CategoryAttributes = CategoryAttributesVersion1 & CategoryAttributesVersion2 &
   CategoryAttributesVersion3 & CategoryAttributesVersion4 & CategoryAttributesVersion5 &
-  CategoryAttributesVersion6
+  CategoryAttributesVersion6 & CategoryAttributesVersion7
 
 export type CategoryModel = Sequelize.Model & CategoryAttributes
 export type CategoryModelStatic = typeof Sequelize.Model & {
@@ -157,13 +161,25 @@ export const attributesVersion6: SequelizeAttributes<CategoryAttributesVersion6>
   }
 }
 
+export const attributesVersion7: SequelizeAttributes<CategoryAttributesVersion7> = {
+  sort: {
+    type: Sequelize.INTEGER,
+    allowNull: false,
+    defaultValue: 0,
+    validate: {
+      min: 0
+    }
+  }
+}
+
 export const attributes: SequelizeAttributes<CategoryAttributes> = {
   ...attributesVersion1,
   ...attributesVersion2,
   ...attributesVersion3,
   ...attributesVersion4,
   ...attributesVersion5,
-  ...attributesVersion6
+  ...attributesVersion6,
+  ...attributesVersion7
 }
 
 export const createCategoryModel = (sequelize: Sequelize.Sequelize): CategoryModelStatic => sequelize.define('Category', attributes) as CategoryModelStatic
diff --git a/src/database/migration/migrations/20200210-add-category-sorting.ts b/src/database/migration/migrations/20200210-add-category-sorting.ts
new file mode 100644
index 0000000..9cb2ce9
--- /dev/null
+++ b/src/database/migration/migrations/20200210-add-category-sorting.ts
@@ -0,0 +1,39 @@
+/*
+ * server component for the TimeLimit App
+ * Copyright (C) 2019 - 2020 Jonas Lochmann
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as
+ * published by the Free Software Foundation, version 3 of the License.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+import { QueryInterface, Sequelize, Transaction } from 'sequelize'
+import { attributesVersion7 as categoryAttributes } from '../../category'
+
+export async function up (queryInterface: QueryInterface, sequelize: Sequelize) {
+  await sequelize.transaction({
+    type: Transaction.TYPES.EXCLUSIVE
+  }, async (transaction) => {
+    await queryInterface.addColumn('Categories', 'sort', {
+      ...categoryAttributes.sort
+    }, {
+      transaction
+    })
+  })
+}
+
+export async function down (queryInterface: QueryInterface, sequelize: Sequelize) {
+  await sequelize.transaction({
+    type: Transaction.TYPES.EXCLUSIVE
+  }, async (transaction) => {
+    await queryInterface.removeColumn('Categories', 'sort', { transaction })
+  })
+}
diff --git a/src/function/sync/apply-actions/dispatch-parent-action/createcategory.ts b/src/function/sync/apply-actions/dispatch-parent-action/createcategory.ts
index ee16090..484749b 100644
--- a/src/function/sync/apply-actions/dispatch-parent-action/createcategory.ts
+++ b/src/function/sync/apply-actions/dispatch-parent-action/createcategory.ts
@@ -1,6 +1,6 @@
 /*
  * server component for the TimeLimit App
- * Copyright (C) 2019 Jonas Lochmann
+ * Copyright (C) 2019 - 2020 Jonas Lochmann
  *
  * This program is free software: you can redistribute it and/or modify
  * it under the terms of the GNU Affero General Public License as
@@ -37,6 +37,17 @@ export async function dispatchCreateCategory ({ action, cache }: {
     throw new Error('missing child for new category')
   }
 
+  const oldMaxSort: number = await cache.database.category.max('sort', {
+    transaction: cache.transaction,
+    where: {
+      familyId: cache.familyId,
+      childId: action.childId
+    }
+  })
+
+  // if there are no categories, then this is not a number
+  const sort = Number.isSafeInteger(oldMaxSort + 1) ? (oldMaxSort + 1) : 0
+
   // no version number needs to be updated
   await cache.database.category.create({
     familyId: cache.familyId,
@@ -53,7 +64,8 @@ export async function dispatchCreateCategory ({ action, cache }: {
     usedTimesVersion: generateVersionId(),
     parentCategoryId: '',
     blockAllNotifications: false,
-    timeWarningFlags: 0
+    timeWarningFlags: 0,
+    sort
   }, { transaction: cache.transaction })
 
   // update the cache
diff --git a/src/function/sync/apply-actions/dispatch-parent-action/index.ts b/src/function/sync/apply-actions/dispatch-parent-action/index.ts
index 4ce2b0c..87999b8 100644
--- a/src/function/sync/apply-actions/dispatch-parent-action/index.ts
+++ b/src/function/sync/apply-actions/dispatch-parent-action/index.ts
@@ -46,6 +46,7 @@ import {
   UpdateCategoryBatteryLimitAction,
   UpdateCategoryBlockAllNotificationsAction,
   UpdateCategoryBlockedTimesAction,
+  UpdateCategorySortingAction,
   UpdateCategoryTemporarilyBlockedAction,
   UpdateCategoryTimeWarningsAction,
   UpdateCategoryTitleAction,
@@ -86,6 +87,7 @@ import { dispatchSetUserTimezone } from './setusertimezone'
 import { dispatchUpdateCategoryBatteryLimit } from './updatecategorybatterylimit'
 import { dispatchUpdateCategoryBlockAllNotifications } from './updatecategoryblockallnotifications'
 import { dispatchUpdateCategoryBlockedTimes } from './updatecategoryblockedtimes'
+import { dispatchUpdateCategorySorting } from './updatecategorysorting'
 import { dispatchUpdateCategoryTemporarilyBlocked } from './updatecategorytemporarilyblocked'
 import { dispatchUpdateCategoryTimeWarnings } from './updatecategorytimewarnings'
 import { dispatchUpdateCategoryTitle } from './updatecategorytitle'
@@ -148,6 +150,8 @@ export const dispatchParentAction = async ({ action, cache, parentUserId, source
     await dispatchUpdateCategoryBlockAllNotifications({ action, cache })
   } else if (action instanceof UpdateCategoryBlockedTimesAction) {
     await dispatchUpdateCategoryBlockedTimes({ action, cache })
+  } else if (action instanceof UpdateCategorySortingAction) {
+    await dispatchUpdateCategorySorting({ action, cache })
   } else if (action instanceof IncrementCategoryExtraTimeAction) {
     await dispatchIncrementCategoryExtraTime({ action, cache })
   } else if (action instanceof UpdateCategoryTemporarilyBlockedAction) {
diff --git a/src/function/sync/apply-actions/dispatch-parent-action/updatecategorysorting.ts b/src/function/sync/apply-actions/dispatch-parent-action/updatecategorysorting.ts
new file mode 100644
index 0000000..6948cc8
--- /dev/null
+++ b/src/function/sync/apply-actions/dispatch-parent-action/updatecategorysorting.ts
@@ -0,0 +1,45 @@
+/*
+ * server component for the TimeLimit App
+ * Copyright (C) 2019 - 2020 Jonas Lochmann
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as
+ * published by the Free Software Foundation, version 3 of the License.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+import { UpdateCategorySortingAction } from '../../../../action'
+import { Cache } from '../cache'
+
+export async function dispatchUpdateCategorySorting ({ action, cache }: {
+  action: UpdateCategorySortingAction
+  cache: Cache
+}) {
+  // no validation here:
+  // - only parents can do it
+  // - using it over categories which don't belong together destroys the sorting for both,
+  //   but does not cause any trouble
+
+  for (let i = 0; i < action.categoryIds.length; i++) {
+    const categoryId = action.categoryIds[i]
+
+    await cache.database.category.update({
+      sort: i
+    }, {
+      transaction: cache.transaction,
+      where: {
+        familyId: cache.familyId,
+        categoryId
+      }
+    })
+
+    cache.categoriesWithModifiedBaseData.push(categoryId)
+  }
+}
diff --git a/src/function/sync/get-server-data-status.ts b/src/function/sync/get-server-data-status.ts
index 563f4fa..ebc7d2c 100644
--- a/src/function/sync/get-server-data-status.ts
+++ b/src/function/sync/get-server-data-status.ts
@@ -342,7 +342,8 @@ export const generateServerDataStatus = async ({ database, clientStatus, familyI
         'timeWarningFlags',
         'minBatteryCharging',
         'minBatteryMobile',
-        'temporarilyBlockedEndTime'
+        'temporarilyBlockedEndTime',
+        'sort'
       ],
       transaction
     })).map((item) => ({
@@ -358,7 +359,8 @@ export const generateServerDataStatus = async ({ database, clientStatus, familyI
       timeWarningFlags: item.timeWarningFlags,
       minBatteryCharging: item.minBatteryCharging,
       minBatteryMobile: item.minBatteryMobile,
-      temporarilyBlockedEndTime: item.temporarilyBlockedEndTime
+      temporarilyBlockedEndTime: item.temporarilyBlockedEndTime,
+      sort: item.sort
     }))
 
     result.categoryBase = dataForSyncing.map((item): ServerUpdatedCategoryBaseData => ({
@@ -374,7 +376,8 @@ export const generateServerDataStatus = async ({ database, clientStatus, familyI
       timeWarnings: item.timeWarningFlags,
       mblMobile: item.minBatteryMobile,
       mblCharging: item.minBatteryCharging,
-      tempBlockTime: item.temporarilyBlockedEndTime
+      tempBlockTime: item.temporarilyBlockedEndTime,
+      sort: item.sort
     }))
   }
 
diff --git a/src/object/serverdatastatus.ts b/src/object/serverdatastatus.ts
index a58efc4..108b9c0 100644
--- a/src/object/serverdatastatus.ts
+++ b/src/object/serverdatastatus.ts
@@ -108,6 +108,7 @@ export interface ServerUpdatedCategoryBaseData {
   // mbl = minimum battery level
   mblCharging: number
   mblMobile: number
+  sort: number
 }
 
 export interface ServerUpdatedCategoryAssignedApps {