Toast UI Calendar Discontinued — Best Alternatives in 2026

Your Toast UI Calendar dependency hasn't received an update in over four years. The npm package still installs, the demo page still loads, but the library behind it is effectively discontinued — and building on abandoned code means every bug, every security gap, and every framework incompatibility is now your problem. If you're evaluating TUI Calendar for a new project or looking to migrate off it, here are the alternatives worth considering in 2026.

What happened to Toast UI Calendar

Toast UI Calendar (TUI Calendar) was developed by NHN Cloud, a Korean tech company, as part of the broader TOAST UI open-source suite. Version 2.0 launched in mid-2022 as a ground-up TypeScript rewrite that introduced Preact as an internal rendering engine, Immer for state management, and DOMPurify for XSS protection.

The last npm release was v2.1.3 in August 2022. Since then:

• Zero releases in four years — no patches, no minor versions, no security fixes
• ~200 open issues on GitHub with community questions going unanswered
• A stale bot automatically closes valid bug reports after a period of inactivity
• The Vue wrapper (@toast-ui/vue-calendar) explicitly does not support Vue 3
• The React wrapper (@toast-ui/react-calendar) has not been updated for React 18 or 19
• Package health tools like Snyk classify the project's maintenance status as Inactive

NHN Cloud has not published an official end-of-life announcement. Other parts of the TOAST UI suite — particularly the Editor — still see occasional activity. But the calendar component has been silent since 2022, and there are no signs of that changing.

The hidden costs of staying

Running an unmaintained calendar library in production creates compounding risk:

• Security: The bundled Preact, Immer, and DOMPurify versions are frozen at 2022 releases. Any vulnerability discovered after that date is unpatched.
• Compatibility: React 19, Vue 3.4+, and modern bundler configurations (Vite 6, Rspack) may introduce breaking changes that no one upstream will fix.
• Bundle weight: At ~262 KB minified (~81 KB gzipped), TUI Calendar is one of the heaviest calendar libraries available — and you can't tree-shake the bundled internals away.
• Analytics tracking: TUI Calendar sends your site's location.hostname to Google Analytics by default. Disabling it requires an explicit usageStatistics: false flag at init time.

The best Toast UI Calendar alternatives

1. SimpleCalendarJS — lightest option, zero dependencies

SimpleCalendarJS ships ~14 KB gzipped with no dependencies — roughly 6x lighter than TUI Calendar. It covers month, week, and day views with async event fetching, click handlers, drag-and-drop, event resizing, and 34+ built-in locales.

import SimpleCalendarJs from 'simple-calendar-js';
import 'simple-calendar-js/simple-calendar-js.css';

const calendar = new SimpleCalendarJs('#calendar', {
  defaultView: 'month',
  fetchEvents: async (start, end) => {
    const res = await fetch(
      `/api/events?from=${start.toISOString()}&to=${end.toISOString()}`
    );
    return res.json();
  },
  onEventClick: (event) => console.log('Clicked:', event.title),
  onSlotClick: (date) => console.log('Date:', date),
  enableDragAndDrop: true,
  enableResize: true,
});

No framework wrapper needed. The same vanilla JS API works in React, Vue, Svelte, Angular, Astro, or a plain <script> tag. Theming uses CSS custom properties — not a JavaScript config object:

.uc-calendar {
  --cal-primary: #4f46e5;
  --cal-primary-dark: #4338ca;
  --cal-today-bg: #eef2ff;
  --cal-font-size: 14px;
}

Pricing: Free for personal and open-source projects. Commercial projects require a license — $49/year or $199 lifetime per project.

2. FullCalendar — most feature-complete

FullCalendar is the most widely adopted JavaScript calendar library, with over 1 million npm downloads per week and 18,500+ GitHub stars. The plugin architecture lets you install only what you need — the core + daygrid plugin weighs about 47 KB gzipped.

FullCalendar provides first-party React, Vue 3, and Angular connectors. Premium plugins (timeline view, resource scheduling, recurring events) require a commercial license at $480/year per developer. The open-source core covers month, week, day, and list views with drag-and-drop.

Best for: Teams that need resource scheduling, timeline views, or a mature ecosystem with official framework wrappers.

3. react-big-calendar — React-native option

If your stack is React-only, react-big-calendar offers a lighter path at ~30 KB gzipped. It provides month, week, day, and agenda views with a customisable rendering API. The library uses a localizer pattern (date-fns, Day.js, or Moment) for date handling.

The trade-off: it only works in React. No vanilla JS mode, no Vue or Angular support. Actively maintained with regular releases, but the rendering model is less modern than newer alternatives.

Best for: React-only projects that want full control over event rendering without an opinionated UI.

4. DHTMLX Scheduler — enterprise scheduling

DHTMLX Scheduler targets complex resource and timeline scheduling — multi-resource views, recurring events, and Gantt-style timelines. The open-source version (GPL) is free; the commercial license starts at $599 per product.

Best for: Enterprise apps that need DHTMLX's resource management depth and can accept the bundle overhead (~180 KB minified).

Side-by-side comparison

Migrating from Toast UI Calendar

If you're currently running TUI Calendar and planning a migration, here's a practical sequence:

1. Audit your usage. List which TUI Calendar features you actually use — month view, week view, event creation popup, drag-and-drop, milestone schedules, or custom templates. Most applications use less than 30% of a library's API surface.

2. Map features to alternatives. If you only need calendar views and event display, SimpleCalendarJS covers that at a fraction of the bundle weight. If you rely on TUI Calendar's built-in popup UI for event creation, you'll need to build that modal yourself — but you gain full control over the UX.

3. Replace the init code. The migration from TUI Calendar to SimpleCalendarJS is typically straightforward:

// Before: Toast UI Calendar
import Calendar from '@toast-ui/calendar';
import '@toast-ui/calendar/dist/toastui-calendar.min.css';

const calendar = new Calendar('#calendar', {
  defaultView: 'month',
  usageStatistics: false,
});
calendar.createEvents(events);

// After: SimpleCalendarJS
import SimpleCalendarJs from 'simple-calendar-js';
import 'simple-calendar-js/simple-calendar-js.css';

const calendar = new SimpleCalendarJs('#calendar', {
  defaultView: 'month',
  fetchEvents: async () => events,
});

4. Remove the dead weight. Uninstalling @toast-ui/calendar drops ~81 KB gzipped from your bundle and eliminates the bundled Preact, Immer, and DOMPurify — none of which you chose to install.

Summary

• Toast UI Calendar has not shipped a release since August 2022. With ~200 open issues, no framework updates, and Snyk classifying it as Inactive, it is abandoned in all but name.
• The library ships ~81 KB gzipped with Preact, Immer, and DOMPurify bundled — and sends your site's hostname to Google Analytics by default.
• SimpleCalendarJS covers month, week, and day views at ~14 KB gzipped with zero dependencies, drag-and-drop, event resizing, and 34+ locales. Free for personal use, $49/year or $199 lifetime for commercial.
• FullCalendar is the best choice for complex scheduling needs — resource views, timeline, and an ecosystem with 1M+ weekly downloads and official framework wrappers.
• For React-only projects that want rendering control, react-big-calendar at ~30 KB gzipped is a solid middle ground.

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Sources & Further Reading

Research & References

• TOAST UI Calendar GitHub repository — nhn/tui.calendar
• TOAST UI Calendar Issues — nhn/tui.calendar
• @toast-ui/calendar npm package
• @toast-ui/calendar bundle size — Bundlephobia
• @toast-ui/vue-calendar package health — Snyk Advisor
• tui-calendar package health — Snyk Advisor
• FullCalendar — Official Site
• react-big-calendar — npm
• Top JavaScript Scheduler Libraries in 2026 — jqwidgets
• React FullCalendar vs Big Calendar — Bryntum

Image Credits

• Cover: Black Screen With Code — Pexels

All images free to use under the Pexels License.