Sync Overview

2Do for Mac keeps your tasks in step across devices through a sync service of your choice: connect an account you already have, and 2Do reads and writes through it.

If 2Do lives on a single Mac, you can simply leave Sync unconfigured.

Where Sync Lives

Everything sync-related is under 2Do > Settings > Sync. The pane has two tabs:

• Setup — choose your account type, connect, and set per-account options.
• Exclusions — pick lists to keep out of sync (see Sync Exclusions).

The Setup tab starts with an Account Type pop-up ("Sync your lists and tasks across your Macs and mobile devices."). Pick a method there, then connect.

One Account at a Time

2Do syncs through a single active account. Once you connect, the Account Type pop-up is locked, so you can't add a second account or switch by accident. To move to a different method, disconnect the current one first:

• Dropbox connects with Link Account and disconnects with Unlink (confirmed via Remove Linked Device).
• Every other method connects with Connect and switches with Change Account. Choosing Change Account confirms "Change Sync Account — Sync information for the current setup will be reset…", clears the local sync history, and returns the pane to editable so you can pick a new Account Type.

Two switches control whether syncing actually happens:

• Enable Sync — the master switch. Once an account is configured, this gates all syncing.
• Sync automatically — a device-local switch. Turn it off to sync manually (with ⌘S or the Sync toolbar button) on this Mac only. It doesn't affect your other devices.

The Setup footer shows Last Sync (a time, Today at …, or Never) and, when something goes wrong, a red Last Error.

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While a sync is running, the per-account options are temporarily disabled, and the Exclusions tab shows "Options not available while a sync is in progress. Please wait for it to finish." Let the sync finish, then adjust settings.

Sync Methods

Pick one from the Account Type pop-up. Each has its own setup page:

• Dropbox — the recommended method. Syncs your entire 2Do setup through your Dropbox App Folder.
• iCloud CalDAV — Apple-hosted CalDAV. Great for standard tasks; some 2Do-only structure stays on this Mac.
• Fastmail — its own entry in the picker; sign in with your Fastmail address and an app password.
• Custom CalDAV — Nextcloud, ownCloud, Synology, Kerio, SabreDAV, and other CalDAV servers.
• Yahoo — built-in CalDAV entry for Yahoo! Calendar.
• Fruux — built-in CalDAV entry for Fruux.
• Toodledo — for Toodledo users, with web access at toodledo.com.
• Todoist — connects with OAuth in your browser; your Todoist projects appear as 2Do lists.
• Apple Reminders — native EventKit sync so your tasks appear in the Reminders app.
• WebDAV — coming soon. Will sync all of your 2Do data to your own or any WebDAV server, stored as files you control.

The pop-up groups them like this: None; Dropbox; Reminders, Todoist, Toodledo; iCloud CalDAV, Fastmail, Yahoo, Fruux, Custom CalDAV. (WebDAV will join the list when it ships.)

Sharing lists over your local network

Looking to hand a list to someone on the same Wi-Fi network? That's a separate feature, independent of the sync account above: see Share Lists over Wi-Fi.

Choose One Method, Use It Everywhere

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Every device that runs 2Do must use the same sync method and the same account. Mixing methods (for example Dropbox on Mac and iCloud CalDAV on iPhone) leaves you with two disconnected datasets. Set up every device before you start using 2Do day-to-day.

What Syncs and What Stays on This Mac

Each account expands a "What syncs across your devices" section. When a method can't carry something, it shows a "Stays on this Mac" row listing it, plus an interop note and a small help button with more detail. The short version:

• Dropbox — a complete sync method. Everything syncs; nothing stays on this Mac.
• WebDAV (coming soon) — also complete; everything will sync.
• CalDAV (iCloud, Yahoo, Fruux, Custom) — 2Do grouping (List Groups, Tag Groups, Smart Lists) stays on this Mac. "Other apps and devices signed in to this account see your projects and checklists as a flat list of tasks."
• Toodledo — Actions and attachments stay on this Mac, along with Smart Lists, Tag/List groups, and unused tags.
• Todoist and Apple Reminders — attachments and standalone locations stay on this Mac (along with Smart Lists, Tag/List groups, and unused tags).

At-a-Glance Comparison

	Dropbox	iCloud CalDAV	Custom CalDAV	Toodledo	Todoist	WebDAV³	Apple Reminders
Mirrors all 2Do data	✅	partial	partial	partial	partial	✅	partial
Picture & audio attachment	✅	✅¹	✅¹	❌	❌	✅	❌
Locations	✅	✅	✅	✅	❌	✅	❌
List Groups, Tag Groups, Smart Lists	✅	❌	❌	❌	❌	✅	❌
Actions	✅	✅	✅	❌	✅²	✅	✅²
Automatic background sync	✅	✅	✅	✅	✅	✅	✅
Merge Sync	✅	✅	✅	✅	✅	✅	✅
Replace Server Data	✅	✅	✅	✅	❌	✅	❌
Web access	—	iCloud.com	varies	toodledo.com	todoist.com	your server	iCloud.com

¹ A 2Do task can carry one picture and one audio note, and both sync over CalDAV.

² Todoist and Reminders round-trip 2Do-only fields (actions, start dates, and more) as text metadata inside each task's notes/description, so those fields survive between your own 2Do devices. Reminders additionally carries hierarchy identity in that metadata; Todoist uses its native parent/child structure instead.

³ WebDAV is coming soon to 2Do for Mac; see Sync with WebDAV.

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Dropbox is the best all-round choice; WebDAV, once it ships, will be its equivalent for a server you control. Pick Todoist or Apple Reminders when you want your tasks living inside those apps too and can do without attachments and standalone locations.

Merge vs Replace

When two devices already hold data, 2Do needs to know how to combine them. There are three outcomes, and Merge Sync is available for every method.

Merge Sync

Merge will reconcile tasks and lists from this device with the data on the server. 2Do will match existing items where it can and keep both sides in sync. If an item was created separately on both sides and cannot be matched confidently, both copies will be kept.

Merge is the safe default when both sides have real data you want to keep. It never deletes to make the two sides identical. At worst you get a duplicate of an item that couldn't be matched, which you can remove by hand.

Replace Local Data

Replace Local Data will replace the syncable tasks and lists on this device with the data currently on the server. Items that exist only on this device may be removed; the server data is kept.

Use this on a new or empty device that should mirror what's already on the server.

Replace Server Data

Replace Server Data will replace the syncable data on the server with the tasks and lists currently on this device. Items that exist only on the server may be removed, and other devices will receive this device's data on their next sync.

Use this when this Mac holds the data you want everywhere and the server copy is stale, for example right after restoring from a backup.

warning

Replace overwrites one side with the other, so confirm which side holds the tasks you want to keep before picking a direction. Choosing Replace Server Data from an empty Mac, for example, wipes the good copy on the server.

Where You Choose

There are two places the Merge/Replace decision appears:

1. The first-sync prompt. When you connect an account that already has data, 2Do shows a Sync Method alert offering Merge, Replace Local Data, Replace Server Data, and Cancel (only the buttons that apply to that method appear).
2. The Next sync action picker. After the first sync is established, Setup shows a Next sync action picker with Sync Normally, Merge Sync, Replace Local Data, and Replace Server Data. As the footer explains: "Applies only to the next sync. Use it when you need to replace or merge data across devices — it runs once, then returns to Sync Normally."

Either way, 2Do asks you to confirm the choice a second time before it runs. Until the first-sync decision is made, Sync Normally shows as "Will ask before Sync".

Next Sync Action Availability

Not every method offers every action. Todoist and Apple Reminders never offer Replace Server Data: their server is the app you also use directly, and 2Do won't overwrite it wholesale.

Method	Sync Normally	Merge Sync	Replace Local Data	Replace Server Data
Dropbox	✅	✅	✅	✅ (Replace Server (Dropbox) Data)
iCloud CalDAV	✅	✅	✅	✅ (Replace Server (iCloud) Data)
Yahoo / Fruux / Custom CalDAV	✅	✅	✅	✅ (Replace Server (CalDAV) Data)
Toodledo	✅	✅	✅	✅ (Replace Server Data)
WebDAV (coming soon)	✅	✅	✅	✅ (Replace Server Data)
Todoist	✅	✅	✅	❌
Apple Reminders	✅	✅	✅	❌

Sync Exclusions

The Exclusions tab shows your lists, grouped by List Group, each with a switch. Turn a switch on and that list, along with its tasks, stays entirely local to this device. Handy for a scratch list or purely personal notes you don't want leaving the Mac.

Setting Up a New Device

When you install 2Do on a fresh Mac and connect to an account that already holds your data:

1. Open 2Do > Settings > Sync, choose the same Account Type as your other devices, and connect with the same account.
2. On the first-sync prompt, choose Replace Local Data to pull everything down to the new Mac, leaving the server copy untouched. If both sides already have real data, choose Merge Sync instead.

When you've just restored from a backup and this Mac now has the freshest data:

1. Set up sync the same way.
2. On the first-sync prompt, choose Replace Server Data to push your restored data up, replacing the stale server copy so your other devices receive it on their next sync.

If you're unsure which side is freshest, save a backup copy from Settings > Backups before connecting, so you have a recovery point either way.

Switching Sync Methods

To change methods (for example iCloud CalDAV → Dropbox):

1. Save a backup from Settings > Backups (⋯ menu > Save a Copy…) as a safety net.
2. On each device, disconnect the current method (Unlink for Dropbox, Change Account for the others). This resets that device's sync history.
3. Connect the new method on one device first and let it populate the server.
4. Connect the others, choosing Replace Local Data to pull from the freshly populated server (or Merge Sync if a device already has unique data worth keeping).

Tips

tip

Backups are independent of sync. Keep milestone copies from Settings > Backups somewhere safe; even if your sync service has a bad day, you have a recovery path.

tip

Not sure what a method carries? Expand What syncs across your devices under your account in Settings > Sync. The Stays on this Mac row is the authoritative, per-method list of what won't leave this device.