Best Calendar Sync Tools in 2026 (Compared)

Do you juggle more than one calendar — Google for personal, Outlook for work, iCloud on your phone? Keeping them in sync is a chore. You miss meetings that live in only one calendar. You double-book yourself.

This guide compares the best calendar sync tools for 2026. We ranked them on setup time, sync speed, support for Google, Outlook, and iCloud, privacy features, and value for the price.

How did we evaluate these tools?

Each tool was assessed on:

Technical performance:

• Real-time sync — webhooks (instant) or polling (delayed)?
• Bidirectional — can events sync both ways?
• Cross-provider — supports Google Calendar, Outlook, iCloud?
• Duplicate detection — prevents duplicates if the same meeting exists in two calendars?

Privacy and security:

• Privacy controls — can you hide event details, mark events as private?
• Data handling — is calendar data encrypted in transit and at rest?
• Permissions model — what access does the tool request?

Usability:

• Setup time — how long to connect and configure?
• Mobile support — works on iOS and Android?
• UI/UX — intuitive interface or requires technical knowledge?

Pricing:

• Cost — annual subscription cost
• Calendars per plan — how many calendars does each plan support?
• Trial period — can you test before committing?

Support and reliability:

• Documentation — guides, FAQs, troubleshooting resources?
• Support channels — email, chat, etc.?
• Uptime — how reliable is the service?

A note on how we tested. We check Hetk’s sync the hard way. An automated test suite runs every direction across Google, Outlook, and iCloud, plus the privacy modes, recurring events, and deletions. It hits real Google Calendar, Microsoft 365, and Apple iCloud accounts — not mocks or sandboxes. The competitor rows are a different matter. Those come from each vendor’s own docs, feature pages, and pricing as of June 2026. We have not run rival tools through the same harness, so read their rows as “as advertised,” not measured by us.

How do the top calendar sync tools compare?

Competitor pricing, provider support, and sync mechanism verified June 2026 from each vendor’s pricing/feature pages; these may have changed since. Hetk’s own sync behaviour is verified continuously by our automated test suite (see “How we evaluated these tools” below).

Which tools did we review in depth?

Hetk — best value for most users

Price: $15/year Personal, $50/year Professional ($10/$35 early adopter pricing)

Providers: Google Calendar, Microsoft Outlook, Apple iCloud

Key features:

• Real-time bi-directional sync via webhooks (changes appear in seconds)
• Privacy controls (mark private, show as busy, strip content)
• Identity transform (synced events show your email as organizer)
• Automatic duplicate detection
• Supports unlimited calendars; up to 3 sync pairs (Personal) or 8 sync pairs (Professional)
• 21-day free trial with full feature access
• No setup fees or complex configuration

Setup process: Sign in with Google. Add your other providers (Outlook, iCloud). Pick the calendars to sync, choose a direction (one-way or two-way), and set privacy options if you want them. Total time: 2–3 minutes, and you need no technical know-how.

How sync works: Google Calendar changes sync instantly. Google pushes a webhook the moment an event changes, so Hetk hears about it right away. Outlook changes sync within 30–60 seconds. iCloud changes sync by polling every 3–5 minutes. So Google ↔ Outlook is nearly real-time, and iCloud lags a little. These are the intervals our end-to-end tests see against real Google, Microsoft 365, and iCloud accounts.

Privacy in action: Turn on “Mark as Private” and synced events show up as plain “Busy” blocks. The title, description, location, and guest list are all stripped out. That’s handy for pushing personal events onto a work calendar, or for keeping client details to yourself.

Mobile support: Works on iOS and Android via calendar app integration. No native Hetk app required. Changes sync to your phone’s calendar app automatically.

Pros:

• Cheapest option for active users ($15/year is 5–7x cheaper than most alternatives)
• Truly real-time syncing using webhooks
• Strong privacy controls for sensitive schedules
• Simplest setup (no admin approval, no complex configuration)
• Support for all three major providers (Google, Outlook, iCloud)
• Very active development team

Cons:

• Smaller company (newer product, founded 2025)
• Limited brand recognition
• No scheduling/booking features yet

Best for: Individuals who use multiple calendar providers and want to keep them in sync cheaply and easily. If you use Google for personal and Outlook for work, this is the top choice.

Not ideal for: Teams that need scheduling/booking pages or users who require enterprise SLA guarantees.

OneCal — most features

Price: $60–300/year (tiered by calendar count: $60 for 2 calendars, $120 for 5, $300 for 50)

Providers: Google Calendar, Microsoft Outlook, Apple iCloud

Key features:

• Real-time bi-directional sync via webhooks
• Scheduling/booking pages
• Privacy controls (Pro plan only)
• Team sync features
• Calendar intelligence (suggests meeting times)
• Mobile app for iOS and Android

Setup process: Similar to Hetk—sign in, select calendars, configure sync. Slightly more options, which can feel more complex. Setup time: 3–5 minutes.

How sync works: Webhooks drive real-time updates, so changes appear within 1–2 seconds. OneCal’s “calendar intelligence” uses machine learning to suggest good meeting times, which helps with team scheduling.

Scheduling features: OneCal’s main advantage is booking pages. You can share a link where others see your availability and book meetings directly. Useful for customer interactions, freelancing, or team coordination.

Pros:

• Comprehensive feature set suitable for teams
• Real-time updates via webhooks
• Booking pages are useful if you frequently share availability
• Good for teams managing shared calendars
• Established product with larger community

Cons:

• Several times more expensive than Hetk ($60–300/year vs. $15–50/year), and tiers jump steeply with calendar count
• Privacy controls only in Pro tier
• Booking features add complexity if you don’t need them
• Steeper learning curve
• Overkill for personal use

Best for: Teams or organizations that need scheduling features alongside sync. If you manage team calendars, need booking pages, or want calendar intelligence, OneCal has the features.

Not ideal for: Individuals who only want basic sync without team features.

For a deeper look, see the full Hetk vs OneCal comparison — or the OneCal alternative writeup if you’re weighing a switch.

CalendarBridge — sync plus scheduling

Price: $48–384/year (Basic $48 for 2 calendars, Premium ~$96 for 5, Pro $384 for 8)

Providers: Google Calendar, Microsoft Outlook, Apple iCloud

Key features:

• Real-time bi-directional sync
• Bundled scheduling pages (10 booking links) and an AI scheduling assistant on higher tiers
• Unified calendar view
• Customizable sync rules (filter events, choose which calendars to sync)

Setup process: Web interface with more granular control. You can set specific sync rules and filtering. Setup time: 5–10 minutes, slightly more complex than the simplest tools.

How sync works: CalendarBridge advertises real-time sync, with Google and Outlook updates “typically under a minute.” In practice that’s on par with Hetk’s webhook sync. The real differences are price, how deep the privacy controls go, and the bundled scheduling tools.

Customization: CalendarBridge’s sync rules let you sync only events matching certain criteria (keywords, calendars). Useful if you need fine-grained control.

Pros:

• Supports all three major providers (Google, Outlook, iCloud)
• Bundles sync with booking pages and an AI assistant
• More established product than Hetk
• Real-time sync

Cons:

• Pricier than dedicated sync tools, especially the 8-calendar Pro tier ($384/year)
• Calendars are capped per tier (2 / 5 / 8)
• Limited privacy controls
• Pay for bundled scheduling/AI features even if you only need sync

Best for: Users who want calendar sync and booking pages in one tool.

Not ideal for: Users who only need sync and want to pay less, or who need granular privacy controls.

For a deeper look, see the full Hetk vs CalendarBridge comparison — or the CalendarBridge alternative writeup if you’re weighing a switch.

SyncThemCalendars — budget sync option

Price: $48–216/year (Basic $48 for 5 sync relationships, Premium ~$96 for 16, Pro $216 for 36)

Providers: Google Calendar, Microsoft Outlook, Apple iCloud

Key features:

• Real-time bi-directional sync
• Simple, minimal setup
• Unlimited connected accounts and calendars on every tier (metered on sync relationships)
• Event filtering by calendar color

Setup process: Sign in, select which calendars to sync, choose direction. Very streamlined—takes 2–3 minutes. Similar simplicity to Hetk.

How sync works: Real-time sync across Google, Outlook, and Apple iCloud. Plans are tiered by how many sync relationships you maintain (5, 16, or 36), not by how many calendars or accounts you connect.

Privacy features: Basic privacy/detail-hiding controls, but less granular than Hetk’s Mark as Private, Show As, and Identity Transform.

Pros:

• Real-time sync across all three major providers, including iCloud
• Unlimited accounts and calendars on every plan
• Lightweight, simple setup
• Higher sync-relationship caps than Hetk at the top tier (up to 36)

Cons:

• Cheapest entry plan ($48/year) still costs more than triple Hetk Personal ($15/year)
• Privacy controls are less granular than Hetk’s
• Smaller community and less active development
• No booking features

Best for: Users who need many distinct sync relationships and want unlimited accounts on a budget.

Not ideal for: Users who want the lowest entry price or the most granular privacy controls.

Zapier — automation platform (overpowered for calendar sync)

Price: $29.99+/month (~$360+/year minimum)

Providers: Any service with Zapier integration (Google Calendar, Outlook, Slack, Gmail, Google Sheets, 3,000+ apps)

Key features:

• One-way automation (Zaps)
• Conditional logic (if-then rules)
• Multi-step workflows (e.g., “create a Google event, then send a Slack notification”)
• Integrates with any service Zapier supports

Setup process: There’s no automatic two-way sync. You build a separate Zap for each direction — one for Google → Outlook, another for Outlook → Google. Each Zap runs on a schedule (every 15 minutes, hourly, and so on), not the instant an event changes. Setup takes 10–20 minutes per direction, and you need to learn how Zaps work.

How sync works: It polls. Zapier checks your calendars on a schedule rather than reacting to each change. On the cheapest plan it checks every 15 minutes, so you live with 15-minute delays. Want it faster? You pay for a higher plan.

One-way only: Zapier is fundamentally built for one-way workflows. Creating true two-way sync requires multiple Zaps:

• Zap 1: Google events → Outlook
• Zap 2: Outlook events → Google
• Zap 3: Watch for deletions and delete them in the other calendar
• Zap 4: Watch for updates and update the other calendar

This is complex, error-prone, and not as reliable as purpose-built sync tools.

Pros:

• Extremely flexible for complex automations
• Can integrate with any service
• Can add conditional logic (only sync certain events)

Cons:

• One-way only (doesn’t handle true bi-directional sync well without workarounds)
• Very expensive for simple sync (Zapier’s paid tiers run many times Hetk’s price)
• Steep learning curve
• Slow sync (15+ minute delays)
• Requires multiple Zaps to approximate two-way sync
• Overkill if you only need calendar sync

Best for: Users who need calendar sync plus other automations (sync calendar to Google Sheets, send Slack notification when busy, create Asana tasks from events). Only use if you’re already a Zapier user integrating multiple services.

Not ideal for: Anyone who only wants calendar sync.

OGCS (OpenCalendarSync) — free but limited

Price: Completely free (open-source)

Providers: Google Calendar, Microsoft Outlook (iCloud not supported)

Key features:

• Open-source (code available on GitHub)
• Bi-directional sync
• Runs on Windows desktop only
• Manual sync (you click a button to sync)

Setup process: Download the Windows app, run it, authenticate with your calendar providers, click “Sync” whenever you want to sync. Setup time: 5–10 minutes. Requires some technical comfort.

How sync works: It’s manual. You click a “Sync” button whenever you want your calendars to line up. That’s a world away from automatic sync — you have to remember to press the button. It’s fine if you only sync now and then.

Privacy: No privacy controls. Events sync with all their details.

Reliability: No company stands behind it. Volunteers keep it running, so fixes can be slow to land. And when Google or Microsoft change their calendar APIs, the community has to catch up on its own time — there’s no paid team on call.

Pros:

• Completely free
• No privacy concerns (open-source code available to audit)
• Works offline
• No third-party service
• Good for developers who want to understand how sync works

Cons:

• Windows-only
• Requires manual sync (you click a button)
• No iCloud support
• Outdated UI
• Limited community support and slow bug fixes
• Requires some technical knowledge

Best for: Developers who want a free, open-source solution and don’t mind Windows-only and manual sync. Or users who want to sync occasionally without a subscription.

Not ideal for: Non-technical users, anyone using Mac/Linux, anyone needing automatic sync, or anyone using iCloud.

Native ICS Subscriptions — DIY option (free)

Price: Free (built into all calendar apps)

How it works: You subscribe to a calendar URL in Google Calendar, Outlook, or iCloud. The file behind that URL is an iCalendar (.ics) feed, the open standard every major calendar app can read. No account or login needed — just the URL.

Setup process: Copy a calendar’s public ICS URL, paste it into your other calendar app’s “Add from URL” field. Takes 1–2 minutes.

How sync works: Your calendar app periodically checks the shared URL for updates. Most calendar apps check every 12–24 hours. This is very slow.

Example workflow: Your friend shares their Google Calendar via an ICS URL. You add it to Outlook. Outlook downloads the calendar’s events and checks for updates every 24 hours. If your friend adds a new event, you might not see it for up to 24 hours.

Privacy features: None. All event details are visible or nothing is visible.

Pros:

• Completely free
• No account setup needed for the source calendar (just a URL)
• Works with any calendar app
• Quick setup (2–3 minutes)

Cons:

• Read-only (you can’t edit events)
• One-way only
• Very slow updates (12–24 hours or longer)
• No privacy controls
• No duplicate detection
• No authentication (only works for public calendars)

Best for: Viewing public calendars (holiday schedules, sports team schedules, conference agendas). Not suitable for keeping personal calendars in sync.

Real-world example: You want to see the local sports team’s game schedule in your personal calendar. The team publishes an ICS URL. You add it to Google Calendar, and games appear automatically (though updates may be delayed).

Which calendar sync tool is right for you?

“I want the cheapest option”

Hetk Personal ($15/year)

At $15/year, Hetk beats every alternative including free options. You get real-time two-way sync, privacy controls, and the easiest setup. The 21-day free trial lets you try before committing.

“I use Google and Outlook and want something simple”

Hetk Personal ($15/year)

Hetk is built for exactly this. Click authorize, pick your calendars, and you’re done. No configuration, no learning curve.

“I need to manage team calendars and booking pages”

OneCal or Hetk Professional

If your team needs to share availability and book meetings, OneCal or Hetk Professional (when it launches with booking features) are better choices. OneCal is more established. Hetk Professional will be cheaper when available.

“I use all three providers (Google, Outlook, iCloud)”

Hetk Personal ($15/year)

Hetk is the cheapest tool that covers all three. OneCal, CalendarBridge, and SyncThemCalendars support iCloud too, but they cost more — often several times more at the same usage. The free options fall short: OGCS skips iCloud, and plain ICS subscriptions aren’t real-time or two-way.

“I need complex automation alongside sync”

Zapier (if no alternative fits)

Only use Zapier if you need calendar sync plus other automations (Slack notifications, task creation, etc.). Even then, it’s expensive. For pure calendar sync, it’s overkill.

“I want to avoid cloud services”

OGCS (free, desktop only)

If privacy and offline control are paramount, OGCS is free and open-source. You’re limited to Windows desktop and manual sync though.

So what’s the best calendar sync tool in 2026?

For most people, Hetk at $15/year is the best choice. It’s the cheapest real-time sync tool, it supports all three major providers, and it has the strongest privacy controls. The 21-day free trial means you can test it risk-free.

Does your team need booking features, or do you want a more established product? Then OneCal is the alternative. Expect to pay several times more, though — $60–300/year versus Hetk’s $15–50.

For everyone else using ICS subscriptions or struggling with manual sync, Hetk will save you time and prevent double-bookings.

Related

• Hetk vs OneCal
• Hetk vs CalendarBridge
• How to sync Google Calendar with Outlook