diff --git a/packages/frontend/core/package.json b/packages/frontend/core/package.json
index feefab7043..a0847b3620 100644
--- a/packages/frontend/core/package.json
+++ b/packages/frontend/core/package.json
@@ -53,6 +53,7 @@
     "graphemer": "^1.4.0",
     "graphql": "^16.9.0",
     "history": "^5.3.0",
+    "ical.js": "^2.1.0",
     "idb": "^8.0.0",
     "idb-keyval": "^6.2.1",
     "image-blob-reduce": "^4.1.0",
diff --git a/packages/frontend/core/src/desktop/dialogs/setting/workspace-setting/integration/calendar/setting-panel.css.ts b/packages/frontend/core/src/desktop/dialogs/setting/workspace-setting/integration/calendar/setting-panel.css.ts
new file mode 100644
index 0000000000..ccbbe03b22
--- /dev/null
+++ b/packages/frontend/core/src/desktop/dialogs/setting/workspace-setting/integration/calendar/setting-panel.css.ts
@@ -0,0 +1,49 @@
+import { cssVarV2 } from '@toeverything/theme/v2';
+import { style } from '@vanilla-extract/css';
+
+export const list = style({
+  display: 'flex',
+  flexDirection: 'column',
+  gap: 24,
+});
+
+export const newButton = style({
+  color: cssVarV2.text.secondary,
+});
+
+export const newDialog = style({
+  maxWidth: 480,
+});
+
+export const newDialogHeader = style({
+  display: 'flex',
+  alignItems: 'center',
+  gap: 8,
+});
+
+export const newDialogTitle = style({
+  fontSize: 15,
+  lineHeight: '24px',
+  fontWeight: 500,
+  color: cssVarV2.text.primary,
+});
+
+export const newDialogContent = style({
+  marginTop: 16,
+  marginBottom: 20,
+});
+
+export const newDialogLabel = style({
+  fontSize: 12,
+  lineHeight: '20px',
+  fontWeight: 500,
+  color: cssVarV2.text.primary,
+  marginBottom: 4,
+});
+
+export const newDialogFooter = style({
+  display: 'flex',
+  justifyContent: 'flex-end',
+  alignItems: 'center',
+  gap: 20,
+});
diff --git a/packages/frontend/core/src/desktop/dialogs/setting/workspace-setting/integration/calendar/setting-panel.tsx b/packages/frontend/core/src/desktop/dialogs/setting/workspace-setting/integration/calendar/setting-panel.tsx
new file mode 100644
index 0000000000..3aec8fdac5
--- /dev/null
+++ b/packages/frontend/core/src/desktop/dialogs/setting/workspace-setting/integration/calendar/setting-panel.tsx
@@ -0,0 +1,123 @@
+import { Button, Input, Modal, notify } from '@affine/component';
+import { IntegrationService } from '@affine/core/modules/integration';
+import { useI18n } from '@affine/i18n';
+import { PlusIcon, TodayIcon } from '@blocksuite/icons/rc';
+import { useLiveData, useService } from '@toeverything/infra';
+import { useCallback, useState } from 'react';
+
+import { IntegrationCardIcon } from '../card';
+import { IntegrationSettingHeader } from '../setting';
+import * as styles from './setting-panel.css';
+import { SubscriptionSetting } from './subscription-setting';
+
+export const CalendarSettingPanel = () => {
+  const t = useI18n();
+  const calendar = useService(IntegrationService).calendar;
+  const subscriptions = useLiveData(calendar.subscriptions$);
+  return (
+    <>
+      <IntegrationSettingHeader
+        icon={<TodayIcon />}
+        name={t['com.affine.integration.calendar.name']()}
+        desc={t['com.affine.integration.calendar.desc']()}
+        divider={false}
+      />
+      <div className={styles.list}>
+        {subscriptions.map(subscription => (
+          <SubscriptionSetting
+            key={subscription.url}
+            subscription={subscription}
+          />
+        ))}
+        <AddSubscription />
+      </div>
+    </>
+  );
+};
+
+const AddSubscription = () => {
+  const t = useI18n();
+  const [open, setOpen] = useState(false);
+  const [url, setUrl] = useState('');
+  const [verifying, setVerifying] = useState(false);
+  const calendar = useService(IntegrationService).calendar;
+
+  const handleOpen = useCallback(() => {
+    setOpen(true);
+  }, []);
+  const handleClose = useCallback(() => {
+    setOpen(false);
+    setUrl('');
+  }, []);
+
+  const handleInputChange = useCallback((value: string) => {
+    setUrl(value);
+  }, []);
+
+  const handleAddSub = useCallback(() => {
+    setVerifying(true);
+    calendar
+      .createSubscription(url)
+      .then(() => {
+        setOpen(false);
+        setUrl('');
+      })
+      .catch(() => {
+        notify.error({
+          title: t['com.affine.integration.calendar.new-error'](),
+        });
+      })
+      .finally(() => {
+        setVerifying(false);
+      });
+  }, [calendar, t, url]);
+
+  return (
+    <>
+      <Button
+        prefix={<PlusIcon />}
+        size="large"
+        onClick={handleOpen}
+        className={styles.newButton}
+      >
+        {t['com.affine.integration.calendar.new-subscription']()}
+      </Button>
+      <Modal
+        open={open}
+        onOpenChange={setOpen}
+        persistent
+        withoutCloseButton
+        contentOptions={{ className: styles.newDialog }}
+      >
+        <header className={styles.newDialogHeader}>
+          <IntegrationCardIcon>
+            <TodayIcon />
+          </IntegrationCardIcon>
+          <div className={styles.newDialogTitle}>
+            {t['com.affine.integration.calendar.new-title']()}
+          </div>
+        </header>
+
+        <div className={styles.newDialogContent}>
+          <div className={styles.newDialogLabel}>
+            {t['com.affine.integration.calendar.new-url-label']()}
+          </div>
+          <Input
+            type="text"
+            value={url}
+            onChange={handleInputChange}
+            placeholder="https://example.com/calendar.ics"
+            onEnter={handleAddSub}
+          />
+        </div>
+
+        <footer className={styles.newDialogFooter}>
+          <Button onClick={handleClose}>{t['Cancel']()}</Button>
+          <Button variant="primary" onClick={handleAddSub} loading={verifying}>
+            {t['com.affine.integration.calendar.new-subscription']()}
+          </Button>
+        </footer>
+      </Modal>
+    </>
+  );
+};
diff --git a/packages/frontend/core/src/desktop/dialogs/setting/workspace-setting/integration/calendar/subscription-setting.css.ts b/packages/frontend/core/src/desktop/dialogs/setting/workspace-setting/integration/calendar/subscription-setting.css.ts
new file mode 100644
index 0000000000..9484f1461a
--- /dev/null
+++ b/packages/frontend/core/src/desktop/dialogs/setting/workspace-setting/integration/calendar/subscription-setting.css.ts
@@ -0,0 +1,84 @@
+import { cssVarV2 } from '@toeverything/theme/v2';
+import { style } from '@vanilla-extract/css';
+
+export const card = style({
+  padding: '8px 16px 12px 16px',
+  borderRadius: 8,
+  background: cssVarV2.layer.background.primary,
+  border: `1px solid ${cssVarV2.layer.insideBorder.border}`,
+  display: 'flex',
+  flexDirection: 'column',
+  gap: 4,
+});
+export const divider = style({
+  height: 8,
+  display: 'flex',
+  alignItems: 'center',
+  justifyContent: 'center',
+  ':before': {
+    content: '',
+    width: '100%',
+    height: 0,
+    borderTop: `0.5px solid ${cssVarV2.tab.divider.divider}`,
+  },
+});
+export const header = style({
+  display: 'flex',
+  alignItems: 'center',
+  gap: 8,
+});
+export const colorPickerTrigger = style({
+  width: 24,
+  height: 24,
+  borderRadius: 4,
+  cursor: 'pointer',
+  background: cssVarV2.layer.background.overlayPanel,
+  border: `1px solid ${cssVarV2.layer.insideBorder.border}`,
+  display: 'flex',
+  alignItems: 'center',
+  justifyContent: 'center',
+  ':before': {
+    content: '',
+    width: 11,
+    height: 11,
+    borderRadius: 11,
+    backgroundColor: 'currentColor',
+  },
+});
+export const colorPicker = style({
+  display: 'flex',
+  gap: 4,
+  alignItems: 'center',
+});
+export const colorPickerItem = style({
+  width: 20,
+  height: 20,
+  borderRadius: 10,
+  display: 'flex',
+  alignItems: 'center',
+  justifyContent: 'center',
+  cursor: 'pointer',
+  selectors: {
+    '&[data-active="true"]': {
+      boxShadow: `0 0 0 1px ${cssVarV2.button.primary}`,
+    },
+    '&:before': {
+      content: '',
+      width: 16,
+      height: 16,
+      borderRadius: 8,
+      background: 'currentColor',
+    },
+  },
+});
+export const name = style({
+  fontSize: 14,
+  fontWeight: 500,
+  lineHeight: '22px',
+  color: cssVarV2.text.primary,
+  width: 0,
+  flexGrow: 1,
+  textOverflow: 'ellipsis',
+  overflow: 'hidden',
+  whiteSpace: 'nowrap',
+});
diff --git a/packages/frontend/core/src/desktop/dialogs/setting/workspace-setting/integration/calendar/subscription-setting.tsx b/packages/frontend/core/src/desktop/dialogs/setting/workspace-setting/integration/calendar/subscription-setting.tsx
new file mode 100644
index 0000000000..e323352c78
--- /dev/null
+++ b/packages/frontend/core/src/desktop/dialogs/setting/workspace-setting/integration/calendar/subscription-setting.tsx
@@ -0,0 +1,87 @@
+import { Button, Menu } from '@affine/component';
+import {
+  type CalendarSubscription,
+  IntegrationService,
+} from '@affine/core/modules/integration';
+import { useI18n } from '@affine/i18n';
+import { useLiveData, useService } from '@toeverything/infra';
+import { useCallback, useMemo, useState } from 'react';
+
+import * as styles from './subscription-setting.css';
+
+export const SubscriptionSetting = ({
+  subscription,
+}: {
+  subscription: CalendarSubscription;
+}) => {
+  const t = useI18n();
+  const [menuOpen, setMenuOpen] = useState(false);
+  const calendar = useService(IntegrationService).calendar;
+  const config = useLiveData(subscription.config$);
+  const name = useLiveData(subscription.name$);
+
+  const handleColorChange = useCallback(
+    (color: string) => {
+      calendar.updateSubscription(subscription.url, { color });
+      setMenuOpen(false);
+    },
+    [calendar, subscription.url]
+  );
+
+  const handleUnsubscribe = useCallback(() => {
+    calendar.deleteSubscription(subscription.url);
+  }, [calendar, subscription.url]);
+
+  if (!config) return null;
+
+  return (
+    <div className={styles.card}>
+      <div className={styles.header}>
+        <Menu
+          rootOptions={{ open: menuOpen, onOpenChange: setMenuOpen }}
+          contentOptions={{ alignOffset: -6 }}
+          items={
+            <ColorPicker
+              activeColor={config.color}
+              onChange={handleColorChange}
+            />
+          }
+        >
+          <div
+            className={styles.colorPickerTrigger}
+            style={{ color: config.color }}
+          />
+        </Menu>
+        <div className={styles.name}>{name || t['Untitled']()}</div>
+        <Button variant="error" onClick={handleUnsubscribe}>
+          {t['com.affine.integration.calendar.unsubscribe']()}
+        </Button>
+      </div>
+    </div>
+  );
+};
+
+const ColorPicker = ({
+  activeColor,
+  onChange,
+}: {
+  onChange: (color: string) => void;
+  activeColor: string;
+}) => {
+  const calendar = useService(IntegrationService).calendar;
+  const colors = useMemo(() => calendar.colors, [calendar]);
+
+  return (
+    <ul className={styles.colorPicker}>
+      {colors.map(color => (
+        <li
+          key={color}
+          onClick={() => onChange(color)}
+          data-active={color === activeColor}
+          className={styles.colorPickerItem}
+          style={{ color }}
+        />
+      ))}
+    </ul>
+  );
+};
diff --git a/packages/frontend/core/src/desktop/dialogs/setting/workspace-setting/integration/constants.tsx b/packages/frontend/core/src/desktop/dialogs/setting/workspace-setting/integration/constants.tsx
index 578b46712d..5f3a720a78 100644
--- a/packages/frontend/core/src/desktop/dialogs/setting/workspace-setting/integration/constants.tsx
+++ b/packages/frontend/core/src/desktop/dialogs/setting/workspace-setting/integration/constants.tsx
@@ -1,23 +1,59 @@
+import type { FeatureFlagService } from '@affine/core/modules/feature-flag';
 import { IntegrationTypeIcon } from '@affine/core/modules/integration';
 import type { I18nString } from '@affine/i18n';
+import { TodayIcon } from '@blocksuite/icons/rc';
+import { LiveData } from '@toeverything/infra';
 import type { ReactNode } from 'react';
 
+import { CalendarSettingPanel } from './calendar/setting-panel';
 import { ReadwiseSettingPanel } from './readwise/setting-panel';
 
-export type IntegrationCard = {
+interface IntegrationCard {
   id: string;
   name: I18nString;
   desc: I18nString;
   icon: ReactNode;
   setting: ReactNode;
-};
+}
 
-export const INTEGRATION_LIST: IntegrationCard[] = [
+const INTEGRATION_LIST = [
   {
-    id: 'readwise',
+    id: 'readwise' as const,
     name: 'com.affine.integration.readwise.name',
     desc: 'com.affine.integration.readwise.desc',
     icon: <IntegrationTypeIcon type="readwise" />,
     setting: <ReadwiseSettingPanel />,
   },
-];
+  BUILD_CONFIG.isElectron && {
+    id: 'calendar' as const,
+    name: 'com.affine.integration.calendar.name',
+    desc: 'com.affine.integration.calendar.desc',
+    icon: <TodayIcon />,
+    setting: <CalendarSettingPanel />,
+  },
+] satisfies (IntegrationCard | false)[];
+
+type IntegrationId = Exclude<
+  Extract<(typeof INTEGRATION_LIST)[number], {}>,
+  false
+>['id'];
+
+export type IntegrationItem = Exclude<IntegrationCard, 'id'> & {
+  id: IntegrationId;
+};
+
+export function getAllowedIntegrationList$(
+  featureFlagService: FeatureFlagService
+) {
+  return LiveData.computed(get => {
+    return INTEGRATION_LIST.filter(item => {
+      if (!item) return false;
+
+      if (item.id === 'calendar') {
+        return get(featureFlagService.flags.enable_calendar_integration.$);
+      }
+
+      return true;
+    }) as IntegrationItem[];
+  });
+}
diff --git a/packages/frontend/core/src/desktop/dialogs/setting/workspace-setting/integration/index.tsx b/packages/frontend/core/src/desktop/dialogs/setting/workspace-setting/integration/index.tsx
index 355dd2f175..ebd4341fb4 100644
--- a/packages/frontend/core/src/desktop/dialogs/setting/workspace-setting/integration/index.tsx
+++ b/packages/frontend/core/src/desktop/dialogs/setting/workspace-setting/integration/index.tsx
@@ -1,6 +1,8 @@
 import { SettingHeader } from '@affine/component/setting-components';
+import { FeatureFlagService } from '@affine/core/modules/feature-flag';
 import { useI18n } from '@affine/i18n';
-import { type ReactNode, useState } from 'react';
+import { useLiveData, useService } from '@toeverything/infra';
+import { type ReactNode, useMemo, useState } from 'react';
 
 import { SubPageProvider, useSubPageIsland } from '../../sub-page';
 import {
@@ -8,12 +10,21 @@ import {
   IntegrationCardContent,
   IntegrationCardHeader,
 } from './card';
-import { INTEGRATION_LIST } from './constants';
+import { getAllowedIntegrationList$ } from './constants';
 import { list } from './index.css';
 
 export const IntegrationSetting = () => {
   const t = useI18n();
   const [opened, setOpened] = useState<string | null>(null);
+  const featureFlagService = useService(FeatureFlagService);
+
+  const integrationList = useLiveData(
+    useMemo(
+      () => getAllowedIntegrationList$(featureFlagService),
+      [featureFlagService]
+    )
+  );
+
   return (
     <>
       <SettingHeader
@@ -27,7 +38,7 @@ export const IntegrationSetting = () => {
         }
       />
       <ul className={list}>
-        {INTEGRATION_LIST.map(item => {
+        {integrationList.map(item => {
           const title =
             typeof item.name === 'string'
               ? t[item.name]()
diff --git a/packages/frontend/core/src/desktop/dialogs/setting/workspace-setting/integration/setting.css.ts b/packages/frontend/core/src/desktop/dialogs/setting/workspace-setting/integration/setting.css.ts
index e06f09452b..a74949055d 100644
--- a/packages/frontend/core/src/desktop/dialogs/setting/workspace-setting/integration/setting.css.ts
+++ b/packages/frontend/core/src/desktop/dialogs/setting/workspace-setting/integration/setting.css.ts
@@ -5,9 +5,13 @@ export const header = style({
   display: 'flex',
   alignItems: 'center',
   gap: 8,
-  paddingBottom: 16,
-  borderBottom: '0.5px solid ' + cssVarV2.layer.insideBorder.border,
   marginBottom: 24,
+  selectors: {
+    '&[data-divider="true"]': {
+      paddingBottom: 16,
+      borderBottom: '0.5px solid ' + cssVarV2.layer.insideBorder.border,
+    },
+  },
 });
 export const headerContent = style({
   width: 0,
diff --git a/packages/frontend/core/src/desktop/dialogs/setting/workspace-setting/integration/setting.tsx b/packages/frontend/core/src/desktop/dialogs/setting/workspace-setting/integration/setting.tsx
index 952f02e0bb..c630b42150 100644
--- a/packages/frontend/core/src/desktop/dialogs/setting/workspace-setting/integration/setting.tsx
+++ b/packages/frontend/core/src/desktop/dialogs/setting/workspace-setting/integration/setting.tsx
@@ -11,14 +11,16 @@ export const IntegrationSettingHeader = ({
   name,
   desc,
   action,
+  divider = true,
 }: {
   icon: ReactNode;
   name: string;
   desc: string;
   action?: ReactNode;
+  divider?: boolean;
 }) => {
   return (
-    <header className={styles.header}>
+    <header className={styles.header} data-divider={divider}>
       <IntegrationCardIcon className={styles.headerIcon}>
         {icon}
       </IntegrationCardIcon>
diff --git a/packages/frontend/core/src/modules/feature-flag/constant.ts b/packages/frontend/core/src/modules/feature-flag/constant.ts
index 58cce3b455..fdb9c83e65 100644
--- a/packages/frontend/core/src/modules/feature-flag/constant.ts
+++ b/packages/frontend/core/src/modules/feature-flag/constant.ts
@@ -276,6 +276,13 @@ export const AFFINE_FLAGS = {
     configurable: isCanaryBuild,
     defaultState: false,
   },
+  enable_calendar_integration: {
+    category: 'affine',
+    displayName: 'Enable Calendar Integration',
+    description: 'Enable calendar integration',
+    configurable: false,
+    defaultState: isCanaryBuild,
+  },
 } satisfies { [key in string]: FlagInfo };
 
 // oxlint-disable-next-line no-redeclare
diff --git a/packages/frontend/core/src/modules/integration/entities/calendar-subscription.ts b/packages/frontend/core/src/modules/integration/entities/calendar-subscription.ts
new file mode 100644
index 0000000000..89e4e5d228
--- /dev/null
+++ b/packages/frontend/core/src/modules/integration/entities/calendar-subscription.ts
@@ -0,0 +1,59 @@
+import {
+  catchErrorInto,
+  effect,
+  Entity,
+  fromPromise,
+  LiveData,
+  onComplete,
+  onStart,
+} from '@toeverything/infra';
+import ICAL from 'ical.js';
+import { switchMap } from 'rxjs';
+
+import type {
+  CalendarStore,
+  CalendarSubscriptionConfig,
+} from '../store/calendar';
+
+export class CalendarSubscription extends Entity<{ url: string }> {
+  constructor(private readonly store: CalendarStore) {
+    super();
+  }
+
+  config$ = LiveData.from(
+    this.store.watchSubscription(this.props.url),
+    {} as CalendarSubscriptionConfig
+  );
+  content$ = LiveData.from(
+    this.store.watchSubscriptionCache(this.props.url),
+    ''
+  );
+  name$ = this.content$.selector(content => {
+    if (!content) return '';
+    try {
+      const jCal = ICAL.parse(content ?? '');
+      const vCalendar = new ICAL.Component(jCal);
+      return (vCalendar.getFirstPropertyValue('x-wr-calname') as string) || '';
+    } catch {
+      return '';
+    }
+  });
+
+  url = this.props.url;
+  loading$ = new LiveData(false);
+  error$ = new LiveData<any>(null);
+
+  update = effect(
+    switchMap(() =>
+      fromPromise(async () => {
+        const response = await fetch(this.url);
+        const cache = await response.text();
+        this.store.setSubscriptionCache(this.url, cache).catch(console.error);
+      }).pipe(
+        catchErrorInto(this.error$),
+        onStart(() => this.loading$.setValue(true)),
+        onComplete(() => this.loading$.setValue(false))
+      )
+    )
+  );
+}
diff --git a/packages/frontend/core/src/modules/integration/entities/calendar.ts b/packages/frontend/core/src/modules/integration/entities/calendar.ts
new file mode 100644
index 0000000000..d6419c6575
--- /dev/null
+++ b/packages/frontend/core/src/modules/integration/entities/calendar.ts
@@ -0,0 +1,93 @@
+import { Entity, LiveData, ObjectPool } from '@toeverything/infra';
+import ICAL from 'ical.js';
+import { Observable, switchMap } from 'rxjs';
+
+import type {
+  CalendarStore,
+  CalendarSubscriptionConfig,
+} from '../store/calendar';
+import { CalendarSubscription } from './calendar-subscription';
+
+export class CalendarIntegration extends Entity {
+  constructor(private readonly store: CalendarStore) {
+    super();
+  }
+
+  private readonly subscriptionPool = new ObjectPool<
+    string,
+    CalendarSubscription
+  >();
+
+  colors = this.store.colors;
+  subscriptions$ = LiveData.from(
+    this.store.watchSubscriptionMap().pipe(
+      switchMap(subs => {
+        const refs = Object.entries(subs ?? {}).map(([url]) => {
+          const exists = this.subscriptionPool.get(url);
+          if (exists) {
+            return exists;
+          }
+          const subscription = this.framework.createEntity(
+            CalendarSubscription,
+            { url }
+          );
+          const ref = this.subscriptionPool.put(url, subscription);
+          return ref;
+        });
+
+        return new Observable<CalendarSubscription[]>(subscribe => {
+          subscribe.next(refs.map(ref => ref.obj));
+          return () => {
+            refs.forEach(ref => ref.release());
+          };
+        });
+      })
+    ),
+    []
+  );
+
+  async verifyUrl(_url: string) {
+    let url = _url;
+    try {
+      const urlObj = new URL(url);
+      if (urlObj.protocol === 'webcal:') {
+        urlObj.protocol = 'https';
+      }
+      url = urlObj.toString();
+    } catch (err) {
+      console.error(err);
+      throw new Error('Invalid URL');
+    }
+    try {
+      const response = await fetch(url);
+      const content = await response.text();
+      ICAL.parse(content);
+      return content;
+    } catch (err) {
+      console.error(err);
+      throw new Error('Failed to verify URL');
+    }
+  }
+
+  async createSubscription(url: string) {
+    try {
+      const content = await this.verifyUrl(url);
+      this.store.addSubscription(url);
+      this.store.setSubscriptionCache(url, content).catch(console.error);
+    } catch (err) {
+      console.error(err);
+      throw new Error('Failed to verify URL');
+    }
+  }
+
+  deleteSubscription(url: string) {
+    this.store.removeSubscription(url);
+  }
+
+  updateSubscription(
+    url: string,
+    updates: Partial<Omit<CalendarSubscriptionConfig, 'url'>>
+  ) {
+    this.store.updateSubscription(url, updates);
+  }
+}
diff --git a/packages/frontend/core/src/modules/integration/index.ts b/packages/frontend/core/src/modules/integration/index.ts
index 1d74466920..2c91583f16 100644
--- a/packages/frontend/core/src/modules/integration/index.ts
+++ b/packages/frontend/core/src/modules/integration/index.ts
@@ -3,18 +3,23 @@ import type { Framework } from '@toeverything/infra';
 import { WorkspaceServerService } from '../cloud';
 import { WorkspaceDBService } from '../db';
 import { DocScope, DocService, DocsService } from '../doc';
-import { GlobalState } from '../storage';
+import { CacheStorage, GlobalState } from '../storage';
 import { TagService } from '../tag';
 import { WorkspaceScope, WorkspaceService } from '../workspace';
+import { CalendarIntegration } from './entities/calendar';
+import { CalendarSubscription } from './entities/calendar-subscription';
 import { ReadwiseIntegration } from './entities/readwise';
 import { ReadwiseCrawler } from './entities/readwise-crawler';
 import { IntegrationWriter } from './entities/writer';
 import { IntegrationService } from './services/integration';
 import { IntegrationPropertyService } from './services/integration-property';
+import { CalendarStore } from './store/calendar';
 import { IntegrationRefStore } from './store/integration-ref';
 import { ReadwiseStore } from './store/readwise';
 
 export { IntegrationService };
+export { CalendarIntegration } from './entities/calendar';
+export { CalendarSubscription } from './entities/calendar-subscription';
 export { IntegrationTypeIcon } from './views/icon';
 export { DocIntegrationPropertiesTable } from './views/properties-table';
 
@@ -35,6 +40,14 @@ export function configureIntegrationModule(framework: Framework) {
       ReadwiseStore,
       DocsService,
     ])
+    .store(CalendarStore, [
+      GlobalState,
+      CacheStorage,
+      WorkspaceService,
+      WorkspaceServerService,
+    ])
+    .entity(CalendarIntegration, [CalendarStore])
+    .entity(CalendarSubscription, [CalendarStore])
     .scope(DocScope)
     .service(IntegrationPropertyService, [DocService]);
 }
diff --git a/packages/frontend/core/src/modules/integration/services/integration.ts b/packages/frontend/core/src/modules/integration/services/integration.ts
index 93fdfac5ec..649b099a15 100644
--- a/packages/frontend/core/src/modules/integration/services/integration.ts
+++ b/packages/frontend/core/src/modules/integration/services/integration.ts
@@ -1,5 +1,6 @@
 import { LiveData, Service } from '@toeverything/infra';
 
+import { CalendarIntegration } from '../entities/calendar';
 import { ReadwiseIntegration } from '../entities/readwise';
 import { IntegrationWriter } from '../entities/writer';
 
@@ -8,6 +9,7 @@ export class IntegrationService extends Service {
   readwise = this.framework.createEntity(ReadwiseIntegration, {
     writer: this.writer,
   });
+  calendar = this.framework.createEntity(CalendarIntegration);
 
   constructor() {
     super();
diff --git a/packages/frontend/core/src/modules/integration/store/calendar.ts b/packages/frontend/core/src/modules/integration/store/calendar.ts
new file mode 100644
index 0000000000..3c423c4754
--- /dev/null
+++ b/packages/frontend/core/src/modules/integration/store/calendar.ts
@@ -0,0 +1,150 @@
+import { LiveData, Store } from '@toeverything/infra';
+import { cssVarV2 } from '@toeverything/theme/v2';
+import { exhaustMap, map } from 'rxjs';
+
+import { AuthService, type WorkspaceServerService } from '../../cloud';
+import type { CacheStorage, GlobalState } from '../../storage';
+import type { WorkspaceService } from '../../workspace';
+
+export interface CalendarSubscriptionConfig {
+  color: string;
+  showEvents?: boolean;
+  showAllDayEvents?: boolean;
+}
+type CalendarSubscriptionStore = Record<string, CalendarSubscriptionConfig>;
+
+export class CalendarStore extends Store {
+  constructor(
+    private readonly globalState: GlobalState,
+    private readonly cacheStorage: CacheStorage,
+    private readonly workspaceService: WorkspaceService,
+    private readonly workspaceServerService: WorkspaceServerService
+  ) {
+    super();
+  }
+
+  public colors = [
+    cssVarV2.calendar.red,
+    cssVarV2.calendar.orange,
+    cssVarV2.calendar.yellow,
+    cssVarV2.calendar.green,
+    cssVarV2.calendar.teal,
+    cssVarV2.calendar.blue,
+    cssVarV2.calendar.purple,
+    cssVarV2.calendar.magenta,
+    cssVarV2.calendar.grey,
+  ];
+
+  public getRandomColor() {
+    return this.colors[Math.floor(Math.random() * this.colors.length)];
+  }
+
+  private _getKey(userId: string, workspaceId: string) {
+    return `calendar:${userId}:${workspaceId}:subscriptions`;
+  }
+
+  private _createSubscription() {
+    return {
+      showEvents: true,
+      showAllDayEvents: true,
+      color: this.getRandomColor(),
+    };
+  }
+
+  authService = this.workspaceServerService.server?.scope.get(AuthService);
+  userId$ =
+    this.workspaceService.workspace.meta.flavour === 'local' ||
+    !this.authService
+      ? new LiveData('__local__')
+      : this.authService.session.account$.map(
+          account => account?.id ?? '__local__'
+        );
+  storageKey$() {
+    const workspaceId = this.workspaceService.workspace.id;
+    return this.userId$.map(userId => this._getKey(userId, workspaceId));
+  }
+  getUserId() {
+    return this.workspaceService.workspace.meta.flavour === 'local' ||
+      !this.authService
+      ? '__local__'
+      : (this.authService.session.account$.value?.id ?? '__local__');
+  }
+
+  getStorageKey() {
+    const workspaceId = this.workspaceService.workspace.id;
+    return this._getKey(this.getUserId(), workspaceId);
+  }
+
+  getCacheKey(url: string) {
+    return `calendar-cache:${url}`;
+  }
+
+  watchSubscriptionMap() {
+    return this.storageKey$().pipe(
+      exhaustMap(storageKey => {
+        return this.globalState.watch<CalendarSubscriptionStore>(storageKey);
+      })
+    );
+  }
+
+  watchSubscription(url: string) {
+    return this.watchSubscriptionMap().pipe(
+      map(subscriptionMap => {
+        if (!subscriptionMap) {
+          return null;
+        }
+        return subscriptionMap[url] ?? null;
+      })
+    );
+  }
+
+  watchSubscriptionCache(url: string) {
+    return this.cacheStorage.watch<string>(this.getCacheKey(url));
+  }
+
+  getSubscriptionMap() {
+    return (
+      this.globalState.get<CalendarSubscriptionStore | undefined>(
+        this.getStorageKey()
+      ) ?? {}
+    );
+  }
+
+  addSubscription(url: string, config?: Partial<CalendarSubscriptionConfig>) {
+    const subscriptionMap = this.getSubscriptionMap();
+    this.globalState.set(this.getStorageKey(), {
+      ...subscriptionMap,
+      [url]: {
+        // merge default config
+        ...this._createSubscription(),
+        // update if exists
+        ...subscriptionMap[url],
+        ...config,
+      },
+    });
+  }
+
+  removeSubscription(url: string) {
+    this.globalState.set(
+      this.getStorageKey(),
+      Object.fromEntries(
+        Object.entries(this.getSubscriptionMap()).filter(([key]) => key !== url)
+      )
+    );
+  }
+
+  updateSubscription(
+    url: string,
+    updates: Partial<Omit<CalendarSubscriptionConfig, 'url'>>
+  ) {
+    const subscriptionMap = this.getSubscriptionMap();
+    this.globalState.set(this.getStorageKey(), {
+      ...subscriptionMap,
+      [url]: { ...subscriptionMap[url], ...updates },
+    });
+  }
+
+  setSubscriptionCache(url: string, cache: string) {
+    return this.cacheStorage.set(this.getCacheKey(url), cache);
+  }
+}
diff --git a/packages/frontend/core/src/modules/storage/index.ts b/packages/frontend/core/src/modules/storage/index.ts
index 1e70f32304..369216fcde 100644
--- a/packages/frontend/core/src/modules/storage/index.ts
+++ b/packages/frontend/core/src/modules/storage/index.ts
@@ -1,4 +1,5 @@
 export {
+  CacheStorage,
   GlobalCache,
   GlobalSessionState,
   GlobalState,
diff --git a/packages/frontend/i18n/src/i18n-completenesses.json b/packages/frontend/i18n/src/i18n-completenesses.json
index b6b37aaaa2..1b80bf2f95 100644
--- a/packages/frontend/i18n/src/i18n-completenesses.json
+++ b/packages/frontend/i18n/src/i18n-completenesses.json
@@ -5,13 +5,13 @@
   "de": 99,
   "el-GR": 99,
   "en": 100,
-  "es-AR": 100,
+  "es-AR": 99,
   "es-CL": 100,
   "es": 99,
   "fa": 99,
   "fr": 99,
   "hi": 2,
-  "it-IT": 100,
+  "it-IT": 99,
   "it": 1,
   "ja": 99,
   "ko": 57,
diff --git a/packages/frontend/i18n/src/i18n.gen.ts b/packages/frontend/i18n/src/i18n.gen.ts
index c21543b7de..4ee70257fe 100644
--- a/packages/frontend/i18n/src/i18n.gen.ts
+++ b/packages/frontend/i18n/src/i18n.gen.ts
@@ -7617,6 +7617,34 @@ export function useAFFiNEI18N(): {
       * `Integration properties`
       */
     ["com.affine.integration.properties"](): string;
+    /**
+      * `Calendar`
+      */
+    ["com.affine.integration.calendar.name"](): string;
+    /**
+      * `New events will be scheduled in AFFiNE’s journal`
+      */
+    ["com.affine.integration.calendar.desc"](): string;
+    /**
+      * `Subscribe`
+      */
+    ["com.affine.integration.calendar.new-subscription"](): string;
+    /**
+      * `Unsubscribe`
+      */
+    ["com.affine.integration.calendar.unsubscribe"](): string;
+    /**
+      * `Add a calendar by URL`
+      */
+    ["com.affine.integration.calendar.new-title"](): string;
+    /**
+      * `Calendar URL`
+      */
+    ["com.affine.integration.calendar.new-url-label"](): string;
+    /**
+      * `An error occurred while adding the calendar`
+      */
+    ["com.affine.integration.calendar.new-error"](): string;
     /**
       * `Notes`
       */
diff --git a/packages/frontend/i18n/src/resources/en.json b/packages/frontend/i18n/src/resources/en.json
index 87b59e3a26..fd767d9db5 100644
--- a/packages/frontend/i18n/src/resources/en.json
+++ b/packages/frontend/i18n/src/resources/en.json
@@ -1906,6 +1906,13 @@
   "com.affine.integration.readwise-prop.created": "Created",
   "com.affine.integration.readwise-prop.updated": "Updated",
   "com.affine.integration.properties": "Integration properties",
+  "com.affine.integration.calendar.name": "Calendar",
+  "com.affine.integration.calendar.desc": "New events will be scheduled in AFFiNE’s journal",
+  "com.affine.integration.calendar.new-subscription": "Subscribe",
+  "com.affine.integration.calendar.unsubscribe": "Unsubscribe",
+  "com.affine.integration.calendar.new-title": "Add a calendar by URL",
+  "com.affine.integration.calendar.new-url-label": "Calendar URL",
+  "com.affine.integration.calendar.new-error": "An error occurred while adding the calendar",
   "com.affine.audio.notes": "Notes",
   "com.affine.audio.transcribing": "Transcribing",
   "com.affine.audio.transcribe.non-owner.confirm.title": "Unable to retrieve AI results for others",
diff --git a/yarn.lock b/yarn.lock
index e330507931..777b6ba987 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -442,6 +442,7 @@ __metadata:
     graphemer: "npm:^1.4.0"
     graphql: "npm:^16.9.0"
     history: "npm:^5.3.0"
+    ical.js: "npm:^2.1.0"
     idb: "npm:^8.0.0"
     idb-keyval: "npm:^6.2.1"
     image-blob-reduce: "npm:^4.1.0"
@@ -23272,6 +23273,13 @@ __metadata:
   languageName: node
   linkType: hard
 
+"ical.js@npm:^2.1.0":
+  version: 2.1.0
+  resolution: "ical.js@npm:2.1.0"
+  checksum: 10/2c1ac836a3a87a6958ab5386f26965a70328ca5566dd84fc641726aef893adb43433aa35d7ea576b890e8461ce54995f9fa82bfa32ce8b186b9b9d4788a6f894
+  languageName: node
+  linkType: hard
+
 "iconv-lite@npm:0.4.24, iconv-lite@npm:^0.4.24":
   version: 0.4.24
   resolution: "iconv-lite@npm:0.4.24"