> Quick answer: Five Google Calendar sync tools have a real free tier in 2026: SYNCDATE (2 calendars, ~4-second webhook sync, "Busy" privacy by default), Reclaim.ai Lite (free forever, 1 calendar sync, 2 connected calendars), OGCS (free and open source, Windows desktop, needs Outlook installed), Keeper (2 accounts, 2 calendars per account, 30-minute refresh, and free if you self-host) and SyncGene (1 calendar, 2 accounts, manual sync once a month).
You manage multiple Google Calendars. Work. Personal. Side projects. They're scattered. You want them to line up without paying for another subscription.
The word "free" gets stretched in this category. Some tools mean free forever with limits. Others mean a trial that stops working. This guide only counts the first kind.
How We Picked These
A limited free tier counts. A free trial doesn't. That single rule decides the list. If sync stops working when the clock runs out, the tool isn't free — it's a demo.
Everything below about another company comes from that company's own published pages, captured in July 2026. Where a vendor doesn't publish something — sync speed is the usual gap — this guide says so instead of guessing. We don't run bake-offs against other people's products, so you won't find invented stopwatch numbers here.
Three tools that often show up on "free" lists are not on this one: OneCal, CalendarBridge and SyncThemCalendars all run on trials, with no free plan behind them. They're covered at the end.
> What's the best free way to sync Google calendars? Use SYNCDATE. The free tier syncs 2 Google calendars both ways, with no credit card. Changes show up in about 4 seconds because it uses webhooks, not polling. Events sync as "Busy" by default, so your details stay private. Delete the sync and you choose whether the copied events go with it or stay put.
1. SYNCDATE
Free tier: 2 calendars across 2 accounts. No credit card required.
Paid: Plus €8.99/mo (20 calendars, 5 accounts), Pro €16.99/mo (100 calendars, 20 accounts).
SYNCDATE is a calendar sync utility built for speed and privacy. It uses webhook-based sync, so events appear in seconds rather than on a polling clock. The default mode writes synced events as "Busy", hiding title, description and attendees from the target calendar. Sync runs one-way or two-way. Delete a sync and you choose whether to remove every event it created or leave the copies in place.
Where it fits: work and personal calendars that need to stay separate but visible to each other. Two-way sync means a change on either side shows up on the other.
Specific use case: a freelancer with several client calendars and one personal calendar blocks personal time on each client's schedule to avoid double-booking. One-way sync from personal to each client calendar, set to "Busy". They see blocked time, not what you're doing.
Calendar view: a built-in cross-provider calendar view shows events from every connected calendar on one screen — day, week, month and agenda layouts.
Event filtering: exclusion rules skip all-day events (holidays, OOO) or events matching a title pattern. Rules apply retroactively, and they're on the free plan.
What it supports: Google Calendar, Microsoft Outlook/Office 365 via the Microsoft Graph Calendar API, and iCloud, Fastmail and Nextcloud over CalDAV with two-way sync. iCal feeds work as a read-only source.
Infrastructure: EU hosted on Hetzner in Germany, GDPR compliant. OAuth 2.0 tokens encrypted with AES-256. A 15-minute polling pass backs up the webhooks.
Setup: 3-4 minutes. Authorize Google, pick calendars, set direction.
The free-tier ceiling: 2 calendars. Fine for one work/personal pair, tight for anything else. If you're managing 3 or more Google accounts, see how to sync multiple Google Calendars across accounts — it covers hub-and-spoke setups and the options at each plan tier.
2. Reclaim.ai (Lite)
Free tier: Lite, free forever. 1 calendar sync, 2 connected calendars, 1 user.
Paid: Starter $10/seat/mo billed yearly ($12 monthly), Business $15/seat/mo yearly ($18 monthly), Enterprise $22/seat/mo yearly.
Reclaim is an AI scheduling suite, and calendar sync is one feature inside it. The important part for this list: the free Lite plan is permanent and it includes a working calendar sync. Reclaim describes the feature as syncing and copying events between Google and Outlook calendars to defend your availability across schedules.
Lite also includes focus time, habits, buffer time and smart meetings, with a one-week scheduling range.
Where it fits: you want scheduling automation and a calendar sync from the same tool, and one sync pair is enough.
Providers: Google Calendar and Outlook Calendar. Reclaim's pricing page lists no iCloud, CalDAV or iCal support.
Sync speed: Reclaim publishes no sync speed or interval anywhere on its pricing page, so this guide doesn't state one.
The free-tier ceiling: one calendar sync and two connected calendars. A second sync pair means moving to Starter.
See our Reclaim alternative comparison for the longer version.
3. OGCS (Outlook Google Calendar Sync)
Free tier: the whole thing. Free and open source under MPL-2.0.
Paid: none for the software itself.
OGCS is a Windows desktop application that syncs Google Calendar with Outlook. Its wiki says keeping OGCS "free (as in libre or 'liberty') and open source has been central to its development", and that it stays "fully functional, without any restrictions to its functionality".
It's actively maintained. The most recent release at capture time was v3.0.3 Alpha on 2026-07-12; the latest stable release was v2.12.0 Beta on 2026-01-18, with alpha releases through the first half of 2026.
The real catch is the requirement, not the quality: OGCS runs on Windows and needs a desktop Outlook installation. It supports "all versions of Outlook from Outlook Online to Classic clients 2003 all through to 2024 64-bit". If you're on a Mac, or you only use Outlook on the web, this one is out before price enters the conversation.
Providers: Outlook and Google.
Sync scheduling: the interval is configurable but floors at 15 minutes. Their FAQ: "scheduled syncs are restricted to a maximum frequency of 15 minutes, or 120 minutes if Push Sync is also enabled" — described as fair usage against the shared Google API quota. Push Sync "triggers an automatic sync within 2 minutes of any calendar change within Outlook", so Outlook-side edits move faster than the schedule.
See our OGCS alternative comparison.
4. Keeper
Free tier: 2 linked accounts, 2 calendars per account, 30-minute sync intervals, aggregated iCal feed.
Paid: Pro $5/month ($42/year). Self-hosted instances get Pro features at no cost.
Keeper is an open-source sync engine (AGPL-3.0) with a hosted plan and a self-host option. The vendor describes it as a pull-compare-push engine using incremental sync tokens, with four connector types: Google Calendar (full read/write), Microsoft Outlook via the Graph API (full read/write), generic CalDAV (RFC 4791, including FastMail and iCloud), and read-only iCal/ICS feeds.
Privacy: busy-blocks by default. Their docs: "By default, only busy/free time blocks are shared. Event titles, descriptions, locations, and attendee lists are stripped before syncing." CalDAV passwords and OAuth tokens are encrypted at rest.
Refresh interval: 30 minutes on Free, 1 minute on Pro and on self-hosted instances. Those are the vendor's published refresh figures, not push notifications.
Where it fits: you want to run your own sync service, or you want CalDAV coverage on a free plan and can live with a half-hour refresh.
The free-tier ceiling: the published free limits above. Self-hosting removes them, at the cost of running the thing yourself — the standalone Docker image is ghcr.io/ridafkih/keeper-standalone:2, which bundles the cron, worker, web and api services.
5. SyncGene
Free tier: 1 calendar, 2 accounts, no automatic synchronization, one manual sync per month.
Paid: SyncGene's own prices don't render on their pricing pages, so this guide doesn't quote any. Check their site before you commit.
SyncGene is the veteran on this list. Their FAQ describes the free plan directly: "the number of services to sync is limited to two accounts; automatic synchronization is disabled; manual sync is limited to one time per month… you will be able to synchronize only one Calendar and Contacts folder/group".
Direction: both. "With SyncGene you can choose to synchronize data in one-way or two-way."
Providers: "SyncGene supports iCloud, Google, Microsoft Exchange services."
Worth knowing before you invest setup time: the site currently tells visitors that "SyncGene is evolving into CiraHub, a more powerful sync platform built by the same team you already trust", and points new subscriptions there. No shutdown date is published.
The free-tier ceiling: one manual sync a month is a checkup, not a sync. If you need calendars to track each other during the week, this tier won't do it.
Tools People Expect to See Here — and Why They Aren't
These come up constantly in "free calendar sync" searches. None of them has a free plan.
OneCal. No free tier. Their FAQ is explicit: "All new users are offered 14 days free trial, no credit card required. After that, you'll need to upgrade to a paid plan to continue using OneCal." Plans are $5, $10 and $25 per user per month billed annually (2, 5 and 50 calendars). See OneCal alternative.
CalendarBridge. No free tier either — a trial with no published length. Paid plans are $5, $10 and $40 per month, or $4, $8 and $32 per month billed annually, covering 2, 5 and 8 calendars. See CalendarBridge alternative.
SyncThemCalendars. "Start with a 14-day free trial. No credit card required." After that, $3.99, $7.99 or $17.99 per month. See SyncThemCalendars alternative.
Zapier and IFTTT. Both have permanent free plans — Zapier at $0/month with 100 tasks a month, IFTTT at $0 with 2 applets. Neither pricing page makes any Google Calendar claim, so if you go this route, verify on their integration pages that the triggers you need exist before building a workflow around them. Automation platforms move events on a trigger; they aren't sync engines, and reconciling updates and deletions is on you. See IFTTT Google Calendar sync and Zapier calendar sync.
What to Look For in a Free Sync Tool
1. Is the free plan permanent, or a trial in disguise?
Read the FAQ, not the button. "Start for free" and "free forever" are different products.
2. Does it sync both directions or copy one way?
Two-way means a change on either side appears on the other. One-way works when you have a hub calendar and spokes. Both are legitimate — just know which you're getting.
3. Does it hide event details automatically?
Look for a "Busy" mode that's on by default. If privacy is a per-event checkbox, you will forget it once, and once is enough.
4. How does it find out about changes?
Webhooks fire when the calendar changes. Polling checks on a clock. A desktop tool syncs when your machine is on. That difference decides whether a just-booked meeting blocks the slot before someone else takes it.
5. What happens when you stop?
Ask what happens to the copied events when you disconnect. A tool that cleans up after itself is one you can test without commitment.
Free Tiers, Side by Side
Figures are each vendor's own published limits, captured July 2026. Blank means the vendor publishes no figure — not that the capability is missing.
| Tool | Free plan | Providers | Change detection | Privacy default |
|---|---|---|---|---|
| SYNCDATE | 2 calendars, 2 accounts | Google, Outlook, CalDAV (iCloud/Fastmail/Nextcloud), iCal feeds (read-only) | Webhooks, ~4 sec | "Busy" blocks, automatic |
| Reclaim Lite | 1 calendar sync, 2 calendars, 1 user | Google, Outlook | Not published | Not published |
| OGCS | Unlimited, open source | Google, Outlook (desktop Outlook required) | Scheduled, 15-min floor; Push Sync within 2 min of an Outlook change | Not published |
| Keeper | 2 accounts, 2 calendars per account | Google, Outlook, CalDAV, iCal feeds (read-only) | Refresh every 30 min (1 min on Pro/self-hosted) | Busy/free blocks, automatic |
| SyncGene | 1 calendar, 2 accounts, 1 manual sync/month | iCloud, Google, Microsoft Exchange | Manual only on free | Not published |
Free Ways to Sync Google Calendars Without a Tool
Some people skip tools entirely and try Google's own settings or manual sharing. Here's how those compare.
| Option | Two-way? | Cost | Limit |
|---|---|---|---|
| SYNCDATE free tier | Yes | Free, no credit card | 2 calendars |
| Manual calendar sharing | No (view only) | Free | Shows the other calendar, doesn't copy events |
| Native Google settings | No | Free | No real sync between two accounts |
Sharing and native settings let you see another calendar. They don't copy events into yours, and they don't work across two Google accounts. If events need to actually move both ways, a free sync tool is the only real option.
FAQ
Is there a free way to sync two Google calendars?
Yes. SYNCDATE syncs two Google calendars for free, with no credit card. It works both ways and updates in about 4 seconds. Google's own sharing and settings only let you view another calendar — they do not copy events into yours.
Which calendar sync tools actually have a free tier?
SYNCDATE (2 calendars), Reclaim.ai Lite (1 calendar sync, free forever), OGCS (free and open source), Keeper (2 accounts, 2 calendars per account) and SyncGene (1 calendar, manual sync once a month). OneCal, CalendarBridge and SyncThemCalendars run on trials with no free plan behind them.
Is SYNCDATE really free?
Yes. The free tier covers 2 calendars across 2 accounts, with no credit card and no trial that flips to paid. It includes the same real-time webhook sync (~4 seconds) and automatic "Busy" privacy as the paid plans. You only pay if you need more: Plus is €8.99/month for 20 calendars across 5 accounts.
Can I sync more than 2 calendars for free?
Not on most hosted free plans — SYNCDATE and Keeper both stop at 2, Reclaim Lite at 1 sync, SyncGene at 1 calendar. Two routes go further at no cost: OGCS, if you run Windows with desktop Outlook installed, or self-hosting Keeper, which the vendor says unlocks its Pro features. Otherwise you're looking at a paid plan.
Will syncing calendars slow down Google Calendar?
No. The sync runs in the background against Google's API, not inside your calendar app. You won't notice a performance difference.
Can I sync personal and work Google accounts without sharing passwords?
Yes, for the tools that use OAuth 2.0 — you authorize access without handing over a password, and you can review or revoke it anytime at Google Account permissions. Each account authorizes separately.
What happens if I delete an event from one calendar?
With two-way sync, the event is removed from the other calendar too. With one-way sync, only the source calendar controls deletions.
Can I sync to multiple destinations from one source?
Yes, by setting up separate syncs. Example: your personal calendar syncs to a work calendar and a client calendar. That's either several one-way syncs or several two-way pairs, and it counts against your plan's calendar limit.
What's the cheapest way to sync 5 Google Calendars?
Free options top out well below five calendars, so this is a paid-plan question for hosted tools. SYNCDATE Plus at €8.99/month covers 20 calendars across 5 accounts. If you'd rather not pay, OGCS is free and unrestricted, provided you're on Windows with desktop Outlook installed.
Choose Based on Your Setup
Speed and privacy matter most: SYNCDATE. Webhook sync, "Busy" by default, two-way, and a clean exit that lets you remove what it created in one step (or leave it, your choice).
You're on Windows with Outlook installed and want zero cost, no limits: OGCS.
You want to run your own infrastructure, or you need CalDAV on a free plan: Keeper.
You already use Reclaim for scheduling and need one sync pair: Reclaim Lite is already in your account.
You only need an occasional manual reconcile: SyncGene's free tier does that, though the vendor is steering new subscriptions to CiraHub.
Still deciding? Compare calendar sync tools side by side, or read the step-by-step guide to syncing multiple Google calendars with a hub-and-spoke setup.
Related: [Sync two Google Calendars](/blog/sync-two-google-calendars), [Sync personal and work Google Calendar](/blog/sync-personal-work-google-calendar), [Sync multiple Google Calendars](/blog/sync-multiple-google-calendars), [Google Calendar sharing vs syncing](/blog/google-calendar-sharing-vs-syncing), [Avoid double-booking Google Calendar](/blog/avoid-double-booking-google-calendar), [Is it safe for Google Calendar apps to access your account?](/blog/is-it-safe-google-calendar-app-access), [Best calendar sync tool comparison](/compare/best-calendar-sync-tool-comparison), [OneCal alternative](/compare/onecal-alternative), [Reclaim alternative](/compare/reclaim-alternative), [CalendarBridge alternative](/compare/calendarbridge-alternative), [SyncThemCalendars alternative](/compare/syncthemcalendars-alternative), [IFTTT Google Calendar sync](/compare/ifttt-google-calendar-sync)