feat: Proton Calendar integration via read-only ICS feed

packages/app-store/apps.metadata.generated.ts

@@ -48,6 +48,7 @@ import horizon_workrooms_config_json from "./horizon-workrooms/config.json";
 import { metadata as hubspot__metadata_ts } from "./hubspot/_metadata";
 import { metadata as huddle01video__metadata_ts } from "./huddle01video/_metadata";
 import ics_feedcalendar_config_json from "./ics-feedcalendar/config.json";
+import protoncalendar_config_json from "./protoncalendar/config.json";
 import insihts_config_json from "./insihts/config.json";
 import intercom_config_json from "./intercom/config.json";
 import jelly_config_json from "./jelly/config.json";
@@ -183,6 +184,7 @@ export const appStoreMetadata = {
   "pipedrive-crm": pipedrive_crm_config_json,
   plausible: plausible_config_json,
   posthog: posthog_config_json,
+  protoncalendar: protoncalendar_config_json,
   qr_code: qr_code_config_json,
   raycast: raycast_config_json,
   "retell-ai": retell_ai_config_json,

packages/app-store/apps.server.generated.ts

@@ -53,6 +53,7 @@ export const apiHandlers = {
   "pipedrive-crm": import("./pipedrive-crm/api"),
   plausible: import("./plausible/api"),
   posthog: import("./posthog/api"),
+  protoncalendar: import("./protoncalendar/api"),
   qr_code: import("./qr_code/api"),
   riverside: import("./riverside/api"),
   roam: import("./roam/api"),

packages/app-store/calendar.services.generated.ts

@@ -15,6 +15,7 @@ export const CalendarServiceMap =
         googlecalendar: import("./googlecalendar/lib/CalendarService"),
         "ics-feedcalendar": import("./ics-feedcalendar/lib/CalendarService"),
         larkcalendar: import("./larkcalendar/lib/CalendarService"),
+        protoncalendar: import("./protoncalendar/lib/CalendarService"),
         office365calendar: import("./office365calendar/lib/CalendarService"),
         zohocalendar: import("./zohocalendar/lib/CalendarService"),
       };

packages/app-store/protoncalendar/DESCRIPTION.md

@@ -0,0 +1,3 @@
+Check availability from your Proton Calendar using shareable ICS feed URLs. No OAuth or API keys required — just paste your calendar's ICS link and Cal.com will check it for scheduling conflicts.
+
+Proton Calendar is a privacy-focused calendar from the makers of Proton Mail.

packages/app-store/protoncalendar/api/add.ts

@@ -0,0 +1,90 @@
+import type { NextApiRequest, NextApiResponse } from "next";
+
+import { symmetricEncrypt } from "@calcom/lib/crypto";
+import logger from "@calcom/lib/logger";
+import prisma from "@calcom/prisma";
+
+import getInstalledAppPath from "../../_utils/getInstalledAppPath";
+import appConfig from "../config.json";
+import { BuildCalendarService } from "../lib";
+
+const ALLOWED_HOSTNAMES = ["calendar.proton.me", "calendar.protonmail.com"];
+
+function isAllowedUrl(url: string): boolean {
+  try {
+    const parsed = new URL(url);
+    if (parsed.protocol !== "https:") return false;
+    return ALLOWED_HOSTNAMES.some((host) => parsed.hostname === host || parsed.hostname.endsWith(`.${host}`));
+  } catch {
+    return false;
+  }
+}
+
+export default async function handler(req: NextApiRequest, res: NextApiResponse) {
+  if (req.method === "POST") {
+    const { urls } = req.body;
+
+    if (!Array.isArray(urls) || urls.length === 0) {
+      return res.status(400).json({ message: "At least one ICS feed URL is required" });
+    }
+
+    // Validate all URLs are from Proton domains
+    for (const url of urls) {
+      if (!isAllowedUrl(url)) {
+        return res.status(400).json({
+          message: `Invalid URL: only HTTPS URLs from ${ALLOWED_HOSTNAMES.join(" or ")} are accepted`,
+        });
+      }
+    }
+
+    // Get user
+    const user = await prisma.user.findFirstOrThrow({
+      where: {
+        id: req.session?.user?.id,
+      },
+      select: {
+        id: true,
+        email: true,
+      },
+    });
+
+    const data = {
+      type: appConfig.type,
+      key: symmetricEncrypt(JSON.stringify({ urls }), process.env.CALENDSO_ENCRYPTION_KEY || ""),
+      userId: user.id,
+      teamId: null,
+      appId: appConfig.slug,
+      invalid: false,
+      delegationCredentialId: null,
+    };
+
+    try {
+      const dav = BuildCalendarService({
+        id: 0,
+        ...data,
+        user: { email: user.email },
+        encryptedKey: null,
+      });
+      const listedCals = await dav.listCalendars();
+
+      if (listedCals.length !== urls.length) {
+        throw new Error(`Listed cals and URLs mismatch: ${listedCals.length} vs. ${urls.length}`);
+      }
+
+      await prisma.credential.create({
+        data,
+      });
+    } catch (e) {
+      logger.error("Could not add Proton Calendar feeds", e);
+      return res.status(500).json({ message: "Could not add Proton Calendar feeds" });
+    }
+
+    return res
+      .status(200)
+      .json({ url: getInstalledAppPath({ variant: "calendar", slug: "proton-calendar" }) });
+  }
+
+  if (req.method === "GET") {
+    return res.status(200).json({ url: "/apps/proton-calendar/setup" });
+  }
+}

packages/app-store/protoncalendar/api/index.ts

@@ -0,0 +1 @@
+export { default as add } from "./add";

packages/app-store/protoncalendar/config.json

@@ -0,0 +1,15 @@
+{
+  "name": "Proton Calendar",
+  "title": "Proton Calendar",
+  "slug": "proton-calendar",
+  "dirName": "protoncalendar",
+  "type": "proton-calendar_calendar",
+  "logo": "icon.svg",
+  "variant": "calendar",
+  "categories": ["calendar"],
+  "publisher": "Cal.com, Inc.",
+  "email": "help@cal.com",
+  "description": "Check availability from Proton Calendar using ICS feed URLs. Proton Calendar is a privacy-focused calendar from Proton.",
+  "isTemplate": false,
+  "__createdUsingCli": true
+}

packages/app-store/protoncalendar/index.ts

@@ -0,0 +1,2 @@
+export * as api from "./api";
+export * as lib from "./lib";