Sync Overview

2Do keeps your tasks in step across your devices through a sync service of your choice. You pick a service you already use, and 2Do reads and writes through it.

If 2Do lives on a single iPhone or iPad, you can leave the sync method set to None.

Where Sync Lives

Open Settings from the gear at the bottom of the list panel, then choose Sync. The pane opens with a short introduction and two tabs:

• Setup, where you choose an account type, connect, and set the options for that account.
• Exclusions, where you keep individual lists out of sync (see Sync Exclusions).

Setup starts with an Account Type menu. Pick a method there, fill in whatever that method needs, and tap Set Up Sync.

One Account at a Time

2Do syncs through a single active account. Once you connect, the Account Type menu is locked, so you cannot 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.
• Every other method connects with Set Up Sync and switches with Change Account. Changing the account clears this device's sync history and unlocks the Account Type menu again.

Two switches control whether syncing actually happens:

• Enable Sync, the master switch for the configured account. Its description reads "Turning this off keeps your account and its settings, but stops syncing."
• Sync automatically, a device-local switch. Its description reads "Turn this off to sync manually by pulling down on the task list." It affects this device only.

Below those, Push Sync lets the service wake 2Do when something changes on another device. It is unavailable, with the note Not supported by device settings, when the device cannot receive pushes.

The Setup footer shows Sync in Progress while a sync runs, then Last Sync and, when something goes wrong, a red Last Error.

Sync Methods

The Account Type menu groups the methods like this: None; iCloud, Reminders; Dropbox; Todoist, Toodledo; iCloud CalDAV, Fastmail, Yahoo, Fruux, Custom CalDAV.

• iCloud, marked Recommended. Everything in 2Do syncs through the iCloud account you are already signed in to, with no separate account or password.
• Apple Reminders, native sync so your tasks also appear in the Reminders app.
• Dropbox, which stores nearly all of your 2Do data in its own Dropbox App Folder. Link-only attachments stay on the device.
• Todoist, connected by signing in to Todoist. Your Todoist projects appear as 2Do lists.
• Toodledo, for Toodledo users, with web access at toodledo.com.
• iCloud CalDAV, Apple-hosted CalDAV using your Apple Account and an app-specific password.
• Fastmail, its own entry in the menu. Sign in with your Fastmail address and an app-specific password.
• Yahoo and Fruux, built-in CalDAV entries.
• Custom CalDAV, for Nextcloud, ownCloud, Synology, Kerio, SabreDAV, and other CalDAV servers.

WebDAV sync is coming soon and will appear in this menu when it ships.

Sharing a list over your local network

Handing a list to someone on the same Wi-Fi network is a separate feature, independent of the sync account above. See Share Lists over Wi-Fi.

If Sync Isn't Set Up Yet

Pulling down on the task list is how you sync by hand. Pull down before a method is configured and 2Do offers to help: an alert titled Sync Isn't Set Up explains "You pulled down to sync, but no sync method is set up yet. Set one up to keep your tasks on all your devices." Choose Set Up Sync to open the Sync pane, Not Now to dismiss it, or Don't Remind Me Again to stop the prompt for good.

Choose One Method, Use It Everywhere

warning

Every device that runs 2Do must use the same sync method and the same account. Mixing methods, for example Dropbox on your Mac and iCloud on your iPhone, leaves you with two disconnected sets of data. Set up every device before you start using 2Do day to day.

What Syncs and What Stays on This Device

Each account has an expandable What syncs across your devices section in Settings > Sync. When a method cannot carry something, it lists it as a Stays on this device capsule, along with a note about how other apps on the same account see your data. The short version:

• iCloud is a complete sync method. Dropbox carries the same groups and task fields, plus picture and audio attachments, but link-only attachments and the manual order of the Focus Lists stay on the device.
• CalDAV (iCloud CalDAV, Fastmail, Yahoo, Fruux, Custom CalDAV) leaves 2Do's grouping features (Smart Lists, tag groups, list groups, unused tags) on this device.
• Toodledo leaves Actions and attachments on this device, along with the grouping features above.
• Todoist and Apple Reminders leave attachments and standalone locations on this device, along with the grouping features above.

App preferences are not part of iCloud sync. A few settings are always local to the device that set them, including per-list alert exclusions and a task's own Ring as Alarm choice.

tip

Not sure what a method carries? Expand What syncs across your devices under your account in Settings > Sync. The Stays on this device capsules are the per-method list of what will not leave this device.

At-a-Glance Comparison

	iCloud	Dropbox	iCloud CalDAV	Custom CalDAV	Toodledo	Todoist	Apple Reminders
Mirrors all 2Do data	✅	partial³	partial	partial	partial	partial	partial
Picture & audio attachments	✅	✅	✅¹	✅¹	❌	❌	❌
Locations	✅	✅	✅	✅	✅	❌	❌
List Groups, Tag Groups, Smart Lists	✅	✅	❌	❌	❌	❌	❌
Manual order in Focus Lists	✅	❌	❌	❌	❌	❌	❌
Actions	✅	✅	✅	✅	❌	✅²	✅²
Automatic and background sync	✅	✅	✅	✅	✅	✅	✅
Merge Sync	✅	✅	✅	✅	✅	✅	✅
Replace Server Data	✅	✅	✅	✅	✅	❌	❌
Web access	None	None	iCloud.com	varies	toodledo.com	todoist.com	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 inside each task's notes or description, so those fields survive between your own 2Do devices. Reminders additionally carries hierarchy identity in that text; Todoist uses its native parent and child structure instead.

³ Dropbox does not sync link-only attachments. Its picture and audio attachments do sync.

note

iCloud is the best all-round choice on Apple devices, and Dropbox is its equivalent when you also run 2Do on Android or want your data in a folder you can see. 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 is available for every method.

Merge

Merge reconciles the tasks and lists on this device with the data on the server. 2Do compares every item on both sides, matches existing items where it can, and keeps both copies when an item was created separately on each side and cannot be matched confidently.

Merge is by far the slowest option. Every task and list has to be compared one at a time, so a first merge with a large number of tasks can take a very long time, and the progress bar may appear to stall for long stretches. It is still running, so let it finish.

Choose Merge only when you are unsure which side is complete, or when both sides hold changes you need to keep. If the server already has a complete copy of your data, choose Replace Local Data. If this device has the complete copy and you just want to push it to the server, choose Replace Server Data (not offered for Todoist or Apple Reminders). Merge never deletes to make the two sides identical. At worst you get a duplicate of an item that could not be matched, which you can remove by hand.

Replace Local Data

Replace Local Data replaces 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, and the server data is kept.

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

Replace Server Data

Replace Server Data replaces 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 receive this device's data on their next sync.

Use this when this device 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 device, for example, wipes the good copy on the server.

Where You Choose

The Merge or Replace decision appears in two places:

1. The first-sync prompt. When both the device and the account already hold user data, 2Do shows an alert titled Sync Method asking "This is the first time you're performing sync. How would you like to proceed?" with Replace Local Data, Replace Server Data, Merge, and Cancel. Only the choices that apply to the method appear.
2. The Next sync action picker. Once the first sync is established, Setup shows a Next sync action picker. Use it when you need to replace or merge data across devices. The choice applies to the next sync only and 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 reads 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 will not overwrite it wholesale.

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

Sync Exclusions

The Exclusions tab shows your lists, grouped the way your list panel groups them, each with a switch: "Selected lists, along with their tasks, will be excluded from sync." Turn a switch on and that list, along with its tasks, stays entirely on this device. Useful for a scratch list or personal notes you would rather not send anywhere.

While a Sync Runs

Setting up an account shows its progress in place, moving through Connecting, Checking for Changes, Downloading Changes, Uploading Changes, and Finishing Up.

You can stay in the Sync pane while a sync runs. Options you change there are picked up by the next run, and Change Account remains available.

Setting Up a New Device

When you install 2Do on a new iPhone or iPad and connect to an account that already holds your data:

1. Open Settings > Sync, choose the same account type as your other devices, and connect with the same account.
2. If the device already contains user data and 2Do shows the first-sync prompt, choose Replace Local Data to pull everything down, leaving the server copy untouched. An empty device can complete setup without this prompt. If both sides hold data you want to keep, choose Merge instead and allow extra time, since merging a large number of tasks is slow.

When you have just restored from a backup and this device now holds the freshest data:

1. Set up sync the same way.
2. When 2Do shows 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 are unsure which side is freshest, save a copy from Settings > Backups & Export before connecting, so you have a recovery point either way.

Switching Sync Methods

To change methods, for example from iCloud CalDAV to iCloud:

1. Save a backup from Settings > Backups & Export 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 account.
4. Connect the others, choosing Replace Local Data to pull from the freshly populated account, or Merge if a device already holds unique data worth keeping. Merge is much slower with many tasks.

tip

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

Background Sync on iOS

iOS decides when apps may run in the background, so 2Do asks for time rather than taking it. It syncs when you bring the app to the front, when iOS grants it a background opportunity, and when the service sends a push telling it something changed. Pull down on the task list any time to sync immediately.

While 2Do is open, it finds out sooner when you change something on another device on the same Wi-Fi network, and syncs right away. That is why 2Do asks for Local Network access, the same permission Wi-Fi Sharing uses. If you decline, sync still works and changes just take a little longer to appear; you can change this later under Settings > Privacy & Security > Local Network > 2Do.

If sync feels stale:

• Check iOS Settings > General > Background App Refresh > 2Do and make sure it is on.
• Leave Push Sync on in Settings > Sync.
• Don't force-quit 2Do. Force-quitting tells iOS not to wake the app in the background.
• On poor connections or heavy data days, iOS may delay background cycles.

Learn more in 2Do isn't syncing in the background.