Calendar infrastructure for strict enterprise environments.
A headless scheduling engine and framework-agnostic Web Components. Zero dependencies. MIT licensed. Built for Salesforce Locker Service / Lightning Web Security and strict CSP.
<forcecal-main> — live, drag an eventWhat forceCalendar is
A calendar you can put inside your own product
Month, week, and day views with events, recurring schedules, timezones, and search. You install two packages, add one HTML tag, and connect your data. It is not a hosted service. The code runs entirely inside your application.
Built for places where most JavaScript is not allowed
Large companies restrict what code on their pages may do. A Content Security Policy (CSP) is a browser rule set that, for example, forbids generating code at runtime or injecting styles. Salesforce goes further with Locker Service, a sandbox around every component. Most calendar libraries rely on exactly the techniques these rules block, so they break, often silently.
Why it exists
forceCalendar was written from scratch to work under those rules: no blocked techniques, no third-party code to audit, one MIT license. If your security team has ever rejected a JavaScript library, this is the calendar they will approve.
Salesforce LWC · React · Vue · Angular · plain HTML
<forcecal-main> tagThe visible calendar: month, week, and day views as standard Web Components, themed with CSS variables.
The engine: stores events, expands recurring schedules, handles timezones, finds conflicts, and searches. No UI, no dependencies; usable on its own.
The problem with calendar libraries in enterprise
Locker Service
Most calendar libraries use JavaScript patterns that Locker Service prohibits: eval, dynamic Function constructors, and prototype manipulation.
forceCalendar uses only Locker-safe patterns. No blocked APIs, no runtime code generation.
Strict CSP
Content Security Policy blocks inline styles, eval, and unsafe-inline. Calendar libraries that inject CSS or generate styles at runtime fail silently.
All styling uses CSS custom properties and external stylesheets. No inline style injection.
Security Reviews
Enterprise security teams audit every dependency. A library with 50+ transitive dependencies creates weeks of review work and ongoing supply chain risk.
Zero dependencies means zero supply chain risk. One package to audit, one license to approve.
Started with Salesforce
Most calendar libraries break inside Locker Service, and that is where forceCalendar started. The same zero-dependency architecture works in any strict enterprise environment.
Native LWC Integration
Runs as a Lightning Web Component. Uses real Salesforce data through Apex, not external APIs.
Locker Service Safe
Zero blocked API calls. No eval, no dynamic Function constructors, no prototype manipulation.
All Views Included
Month, week, and day views with event creation, color coding, and full navigation.
Week view with timed events
Day view with event details
Enterprise calendar infrastructure
Salesforce is the flagship integration. The same architecture works anywhere strict security is required.
Salesforce
Shipping now. LWC + Apex with full Locker Service compliance.
Any Web App
Web Components work in React, Vue, Angular, or vanilla JS, with first-party SSR-safe adapters for React and Vue.
Strict CSP
No eval, no inline styles. Works behind the strictest policies.
Air-Gapped
Zero external requests. Runs fully offline with no CDN dependencies.
Two packages, one architecture
Use Core for scheduling logic and Interface for production-ready UI components.
@forcecalendar/core
Pure JavaScript scheduling engine. No DOM, no dependencies. Headless calendar logic for any runtime.
Learn more@forcecalendar/interface
Web Components powered by Core. Framework-agnostic, Shadow DOM encapsulated. Works in React, Vue, Angular, or vanilla JS.
Learn moreLightning Web Component
Built on top of both packages. Loads as a static resource, connects to Salesforce data through Apex. Locker Service safe.
See it runningFive lines to a working calendar
import { Calendar } from '@forcecalendar/core';
import '@forcecalendar/interface';
const calendar = new Calendar({
locale: 'en-US',
timeZone: 'America/New_York'
});
// That's it. <forcecal-main> is ready to use.What’s included
Recurrence Rules
RFC 5545 RRULE support with exceptions, overrides, and timezone-aware expansion for complex enterprise schedules.
Timezone Support
Full IANA timezone database with automatic daylight-saving transitions and cross-timezone conversion.
ICS Import / Export
iCalendar file support for interoperability with Outlook, Google Calendar, and existing enterprise systems.
Conflict Detection
Spatial indexing enables fast overlap detection across large event sets without scanning every event.
Full-Text Search
Built-in search engine with fuzzy matching across event titles, descriptions, and custom fields.
Accessible by Default
Full WAI-ARIA grid semantics and keyboard navigation across month, week, and day views. No extra configuration.
Server-Side & Edge
The DOM-free engine runs in Node, serverless functions, and edge runtimes like Cloudflare Workers that ban eval.
CSS Theming
45+ CSS custom properties for complete visual control without touching JavaScript or Shadow DOM internals.
How it compares
Independent benchmarks against FullCalendar, an excellent and widely-used library. forceCalendar exists for a different niche: strict enterprise environments where most calendar libraries cannot run.
Bundle Size
2.9x smaller total bundle. Fewer bytes to audit, fewer bytes to ship behind corporate firewalls.
Recurrence (RRULE)
The dedicated rrulelibrary is still faster at raw RRULE expansion, but the gap is now roughly 2x on common daily and weekly patterns (it was up to 1,200x before the v2.1–v2.3 engine work); a five-year daily series expands in about half a millisecond either way.
The trade-off: forceCalendar’s recurrence is built-in with zero extra dependencies and applies timezone/DST handling per occurrence, while FullCalendar requires the separate rrule library. At real-world calendar volumes the difference is microseconds per render.
Benchmarks run against published npm packages; sizes are installed (unpacked) package sizes. Full methodology and interactive results available on the dashboard.
View full benchmarkShip a calendar your security team will approve.
One audit, zero dependencies, MIT licensed. Up and running in minutes.