📅 calforge

Make a real "Add to Calendar" link & .ics file — locally, in milliseconds.

🌐 Try the free web app →  ·  fill in an event, get an .ics + provider links. No sign-up, nothing tracked.

That "Add to Calendar" button in marketing emails and event pages? It's almost always powered by a paid, tracking third-party service (AddEvent, AddToCalendar, …). And rolling your own is deceptively hard: the .ics format (RFC 5545) has strict rules — CRLF line endings, 75-octet line folding, escaping ,, ; and \, exact UTC timestamps, UID, DTSTAMP — and one mistake makes Apple Calendar or Outlook silently refuse the file.

calforge generates a spec-correct .ics and the deep-links for Google, Outlook and Yahoo from one event object — with zero dependencies, no service, no tracking, running entirely in your browser or any JS runtime.

📸 Screenshot / demo GIF: ./web/screenshot.png — record the live app filling an event and clicking each calendar button.

Why it exists

• AI can't do this reliably. RFC 5545's folding/escaping/timestamp rules are exact and unforgiving — a chatbot will happily produce an .ics that won't import. A small, tested, deterministic library gets it right every time.
• No third party. "Add to Calendar" widgets phone home and track opens. calforge runs on your machine; the only thing that leaves is the link you share.
• One event in, everything out. A downloadable .ics (Apple Calendar, Outlook desktop) plus Google/Outlook/Yahoo deep-links — from a single call.

Who it's for

Marketers (event invites, webinars, launches), creators (streams, drops, AMAs), operators (maintenance windows, on-call), event organizers, and developers who want a tiny library to power an "Add to Calendar" button without a SaaS.

Install

No install — just open the web app.

Command line:

npx @didrod2539/calforge --title "Standup" --start 2026-07-01T09:00:00 --duration 30 > standup.ics
npx @didrod2539/calforge -t "Conf" --start 2026-09-10 --all-day --location Berlin --links

Library:

npm install @didrod2539/calforge

Published on npm under the @didrod2539 scope (@didrod2539/calforge). The import name matches the package name; everything else is identical.

Zero dependencies. ESM + CJS + TypeScript types. Runs in the browser, Node, Deno and Bun.

CLI

calforge --title <t> --start <when> [options] > event.ics

Required: -t/--title, --start (ISO datetime, or YYYY-MM-DD for all-day). Options: --end, --duration, --all-day, --location, --description, --url, --rrule, --alarm, --links (print provider deep-links), -o/--out.

Usage

Generate an .ics

import { toICS } from "@didrod2539/calforge";

const ics = toICS({
  title: "Product launch 🚀",
  start: "2026-06-01T17:00:00Z",
  durationMinutes: 60,            // or pass `end`
  location: "Zoom",
  description: "Join us for the reveal.",
  alarmMinutes: 30,               // reminder
});
// → valid VCALENDAR text; write it to a .ics file or offer it as a download.

Get "Add to Calendar" links

import { links } from "@didrod2539/calforge";

const l = links({
  title: "Team offsite",
  start: "2026-09-10T09:00:00Z",
  end: "2026-09-10T17:00:00Z",
  location: "Lisbon",
});

l.google;       // https://calendar.google.com/calendar/render?...
l.outlook;      // https://outlook.live.com/calendar/...
l.yahoo;        // https://calendar.yahoo.com/?...
l.icsDataUri;   // data: URI for an <a download> (Apple / Outlook desktop)
l.ics;          // the raw .ics text

All-day & recurring

toICS({ title: "Launch day", start: "2026-12-25", allDay: true });
toICS({ title: "Standup", start: "2026-06-01T09:00:00Z", rrule: "FREQ=WEEKLY;BYDAY=MO,TU,WE,TH,FR" });

Browser download

const ics = toICS(event);
const url = URL.createObjectURL(new Blob([ics], { type: "text/calendar" }));
// <a href={url} download="event.ics">Add to Calendar</a>

API

| Function | Description | | -------- | ----------- | | toICS(event \| event[]) | Build a complete .ics (VCALENDAR) string. | | links(event) | { ics, icsDataUri, google, outlook, office365, yahoo }. | | googleUrl / outlookUrl / office365Url / yahooUrl(event) | Individual provider links. | | icsDataUri(icsText) | A data: URI for downloads. | | normalize(event) | The resolved event (dates, defaults, derived UID). |

EventInput: title, start, end? / durationMinutes?, allDay?, description?, location?, url?, organizer?, geo?, alarmMinutes?, rrule?, status?, uid?, dtstamp?.

FAQ

Does it phone home or track anyone? No. Generation is 100% local — no server, no telemetry, works offline. Provider links open the user's own calendar.

Will the .ics actually import into Apple Calendar / Outlook? Yes — output follows RFC 5545 (CRLF, 75-octet folding, TEXT escaping, UTC DTSTART/DTEND, UID, DTSTAMP), the things that make pickier clients accept it.

What time zone are events in? Timed events are serialized in UTC (…Z), which every calendar interprets correctly. All-day events use floating VALUE=DATE. (Named-VTIMEZONE output is on the roadmap.)

Can I put multiple events in one file? Yes — pass an array to toICS.

How is this different from the ics / ical-generator npm packages? calforge is zero-dependency and browser-first, and it bundles the provider deep-links + a ready data: URI for an "Add to Calendar" UI — not just file generation.

Contributing

Contributions welcome! See CONTRIBUTING.md and the Code of Conduct.

git clone https://github.com/didrod205/calforge.git
cd calforge
npm install
npm test          # run the suite
npm run dev       # run the web app locally

💖 Sponsor

calforge is free, MIT-licensed, and built in spare time. If it saved you a SaaS subscription (or a debugging afternoon), please consider supporting it:

• ⭐ Star this repo — free, and it genuinely helps others find it.
• 🍋 Sponsor via Lemon Squeezy — one-time or recurring support.

Where your support goes: named time-zone (VTIMEZONE) output, attendees & RSVP, a copy-paste "Add to Calendar" web component, recurrence helpers, more providers, keeping the free web app online, and fast issue responses.

License

MIT © calforge contributors