The cloud GWSMO alternative: ContactZapp vs Google Workspace Sync for Outlook
GWSMO is Google's free Windows plug-in for syncing one Google Workspace account with classic desktop Outlook. ContactZapp is a cloud web app that keeps one clean contact list across Google, Microsoft, Apple and CardDAV — with duplicate merging and a 12-month undo history.
Free plan: 2 accounts and 100 synced contacts. No time limit.
Which tool fits your setup?
Both tools sync contacts between Google and Outlook, but they are built for very different setups.
You want cloud sync across all your accounts and devices
- You use a personal @gmail.com account, Outlook.com, iCloud or CardDAV — or more than 1 work or personal account.
- You work on a Mac, use the new Outlook for Windows, use Outlook on the web or want contacts synced while your PC is off.
- You have years of duplicate contacts across Google, Outlook and iCloud and want to merge them without losing numbers, emails or notes.
- You want an automatic backup before the first change and a 12-month history so you can roll back any sync or merge.
You only use classic Outlook on Windows with one Workspace account
- You have a paid Google Workspace account and your admin has turned GWSMO on in the Google Admin console.
- You work only in classic Outlook for Windows (Outlook 2010 to 2021 or the classic Microsoft 365 desktop app) and have local admin rights to install a Windows plug-in.
- You also need Google Workspace mail, calendar, tasks, notes and the Global Address List inside classic Outlook, not just contacts.
- You only sync 1 Google Workspace account with 1 Outlook profile and do not need duplicate merging, iCloud sync or undo history.
How ContactZapp and GWSMO compare
Every GWSMO detail below comes from Google Workspace Admin Help and public Microsoft Q&A reports, checked on 22 October 2026.
| Feature | ContactZapp | Google Workspace Sync for Outlook (GWSMO) |
|---|---|---|
| How it runs | Cloud web app — runs in the background with your computer off | Windows desktop plug-in — runs only while classic Outlook is open on your PC |
| Supported platforms | Yes: Any browser on Windows, Mac, Linux, iPhone, iPad or Android | No: Classic Outlook for Windows only (no Mac, no New Outlook for Windows, no web or mobile) |
| Personal @gmail.com accounts | Yes: Works with personal Gmail and Google Workspace | No: Paid Google Workspace accounts only |
| Microsoft accounts supported | Yes: Microsoft 365 work accounts, Outlook.com and Hotmail | Local classic Outlook profile only |
| Apple iCloud and CardDAV | Yes: Syncs Apple iCloud and any CardDAV server alongside Google and Microsoft | No: Not supported |
| Multiple accounts per service | Yes: Connect 2 accounts on Free, 3 on Easy or unlimited on Unlimited | No: 1 Google Workspace account and 1 Outlook profile |
| Sync direction | Yes: Two-way or read-only per account | Two-way between Google Workspace and your local Outlook profile |
| Sync schedule | Hourly, daily or manual (starts on manual so you stay in control) | Every 20 minutes and at Outlook startup |
| Contact fields synced | Yes: Names, emails, phones, addresses, company, job title, notes, birthdays, photos, websites, related people, IM, custom fields and labels | Yes: Outlook contact fields including File As, photos, notes and user-defined fields |
| Notes, categories and folders | Yes: Syncs labels and groups across accounts; you choose which labels sync per account | Notes over 16 KB are cut short in Google; Outlook flags and categories do not carry over; separate contact folders are flattened into 1 list |
| Duplicate finding and merging | Yes: Finds duplicates within and across accounts; side-by-side manual merge or optional Auto-Merge | No: No duplicate detection or merging |
| Pre-sync backup | Yes: Automatic backup before the first change, plus up to 5 saved vCard backups per account | No: No automatic backup; "Delete and re-sync" can overwrite local Outlook data or delete contact photos |
| Undo and change history | Yes: Every change is kept for 12 months; roll back 1 contact, 1 sync run or everything | No: No undo history |
| Mail, calendar, tasks and GAL | No: Contacts only — built to do one job well | Yes: Syncs mail, calendar, tasks, notes and the Workspace Global Address List |
| Price | Free plan (2 accounts, 100 contacts synced, no time limit). Paid plans from $9.99 / €8.99 a month | Free with a paid Google Workspace subscription |
Swipe the table to see every column
No Windows plug-in, no classic-Outlook lock-in
GWSMO was built for an older way of working: a Windows PC running classic Outlook against a single Google Workspace mailbox. If you move to a Mac, switch to the new Outlook for Windows or use a personal Gmail account alongside work, GWSMO stops being an option.
ContactZapp runs in the cloud. You connect your accounts once in the browser, and your contacts stay in sync across Google, Microsoft, Apple iCloud and CardDAV without installing software on your computer. Your phone and desktop apps get the updated contacts through the accounts they already sync with.
- Personal and work accounts together: Connect personal Gmail, Google Workspace, Outlook.com, Microsoft 365, Apple iCloud and CardDAV in one place.
- Works with any Outlook client: Because ContactZapp syncs with your Microsoft account in the cloud, your contacts appear in New Outlook for Windows, Outlook for Mac, Outlook on the web and mobile.
- Read-only when you need it: Set any account to read-only if you want to pull its contacts in without ever writing back to it.
Clean up duplicates instead of copying them across
When you connect two contact lists that have grown apart for years, syncing alone copies every duplicate from one side to the other. GWSMO moves contacts between Google Workspace and classic Outlook, but it has no tool to find or merge duplicates.
ContactZapp finds the same person within one account and across accounts by name, email, phone and address. You can review matches side by side or turn on Auto-Merge when you are ready.
- Merges keep every detail: When you merge two contacts, ContactZapp keeps every phone number, email and address instead of dropping one. For single fields like job title or photo, the newest value wins, or you can pick a primary account.
- Prefers the fuller version: When two accounts write the same detail differently, ContactZapp keeps "John Doe Jr" over "J. Doe", a phone number with its country code over one without and an address with the postcode over one without.
- Labels and custom fields carry over: GWSMO flattens separate Outlook contact folders into one list and drops Outlook categories. ContactZapp syncs labels and groups across accounts, lets you choose which labels sync per account and carries custom fields (label and value) across Google, Microsoft, iCloud and CardDAV.
Every change is reversible for 12 months
Desktop sync plug-ins are stressful when something goes wrong. In GWSMO, fixing a broken contact sync often means running "Delete and re-sync", which Google documents can overwrite Outlook-specific data or permanently delete contact photos. In June 2025, GWSMO version 4.3.73.0 also caused classic Outlook to freeze or crash until users rolled back the installer or disabled Google Contacts sync.
ContactZapp is built so you can test and sync without risking your address book. Nothing runs behind your back on day one, and every change can be undone.
- Starts on manual sync: New accounts start on manual sync with Auto-Merge turned off. You see what ContactZapp found before you turn on hourly or daily sync.
- Automatic backup before the first write: We back up each account before the first change and let you keep up to 5 downloadable vCard backups per account.
- 12-month rollback: Every change is kept for 12 months. You can roll back one contact, one sync run or everything, and the rollback is sent to your connected accounts.
Move from GWSMO to ContactZapp in 3 steps
You do not need to wipe your Outlook profile or start from scratch. Connect your accounts, clean up any duplicates and let ContactZapp keep them in sync from the cloud.
- STEP 01
Connect your Google and Microsoft accounts
Sign in to ContactZapp in your browser and connect your Google account (Workspace or personal Gmail) and your Microsoft account, plus Apple iCloud or CardDAV if you use them. ContactZapp backs up each account before making the first change.
- STEP 02
Review and merge duplicates
Check the duplicates GWSMO left behind across your accounts. Merge them side by side — keeping every phone number, email and address — or turn on Auto-Merge. Every merge can be undone for 12 months.
- STEP 03
Turn off GWSMO contact sync and pick your schedule
If you still use GWSMO for mail or calendar in classic Outlook, uncheck Contacts in the GWSMO sync settings so the two tools do not fight each other. Then switch ContactZapp from manual sync to daily or hourly.
Questions about GWSMO and ContactZapp
Why does Google Workspace Sync for Outlook not work with my @gmail.com account?
Google built GWSMO only for paid Google Workspace accounts managed through work, school or another organisation. It does not let you sign in with a personal @gmail.com address. ContactZapp works with both personal Gmail and Google Workspace accounts, and can sync both at the same time.
Does GWSMO work on Mac or in the new Outlook for Windows?
No. GWSMO is a Windows-only plug-in for classic desktop Outlook (Outlook 2010 to 2021 and the classic Microsoft 365 desktop app). It does not support Outlook for Mac, the new Outlook for Windows, Outlook on the web or mobile apps. ContactZapp runs in the cloud and syncs with your Microsoft account directly, so your contacts appear in every Outlook app on every device.
Can I keep using GWSMO for email and calendar while ContactZapp handles my contacts?
Yes. In classic Outlook on Windows, open your GWSMO settings in the Windows system tray and uncheck Contacts sync while leaving Mail and Calendar checked. That way GWSMO stops touching your address book and ContactZapp manages your contacts cleanly.
Do I need my Google Workspace admin or Windows admin rights to use ContactZapp?
ContactZapp is a web app, so there is nothing to install on your Windows PC and no local Windows admin prompt. You connect your own Google and Microsoft accounts in the browser. If your company's IT blocks third-party apps on work accounts, ask them to approve ContactZapp.
What happens to my Outlook contact folders, categories and custom fields?
GWSMO flattens separate Outlook contact folders into a single list, drops Outlook categories and cuts off notes over 16 KB in Google. ContactZapp syncs labels and groups across accounts (you choose which labels sync per account), keeps custom fields with their label and value across Google, Microsoft, iCloud and CardDAV, and waits for a later sync if a Microsoft custom-field set exceeds 16 KB instead of cutting it short.
Can I try ContactZapp before paying?
Yes. The free plan connects 2 accounts and syncs 100 contacts between them, with no time limit and no credit card. It works with an address book of any size — contacts past 100 stay safe in each account until you upgrade. Paid plans also carry a 14-day money-back guarantee, no questions asked, on your first purchase.
Ready to sync Google and Outlook contacts without a Windows plug-in?
Connect 2 accounts on the free plan. Sync 100 contacts, merge duplicates and keep a 12-month undo history — no credit card and no time limit.