I prefer applications that provide some sort of syncing service. This is pretty advantageous compared to other apps, since you don’t need to worry about backing anything up in case you restore your iPhone (or if you lose it), and you can use the same information from different devices and even different services. For example, you can use Wunderlist from nearly any device or computer, even a browser, which is a lot more comfortable than just having your tasks on your iPhone.
Considering the advantage of having an app that syncs with any service, here’s a list of approximately 40 apps that have this functionality.
Task Management
2Do
This is an amazing task manager app. It’s compatible with both the iPhone and iPad, and syncs with your Mac or PC via Wi-Fi, Toodledo and iCloud. It’s a great choice if you want an app that’s compatible with iOS 5′s new Reminders app.
Price: $6.99
Developer: Guided Ways Technologies Ltd
Download: App Store
Wunderlist
You probably already know Wunderlist. It’s a great (and free) task manager app, compatible with the iPhone and iPad, and syncs with the Wunderlist service, allowing you to manage your Todos from any device — including the web. It’s also customizable, allowing you to change backgrounds, and it even allows you to share task lists with friends.
Price: Free
Developer: 6 Wunderkinder
Download: App Store
Toodledo
Yet another Todo manager. This app syncs directly with Toodledo’s service, which was originally available on the web only. You can manage lists, notes, tasks, attach geolocation and even get location-based reminders. It’s a very practical app and pretty cheap too.
Price: $2.99
Developer: Toodledo
Download: App Store
Todo
This is a pretty famous task manager on the App Store. Combining a beautiful and simple interface, and having support for the GTD method, it’s a great app. It syncs with Dropbox, Toodledo, iCal, Outlook and its own (paid) cloud service. iCloud support is coming later this year.
Price: $4.99
Developer: Appigo
Download: App Store
gTasks HD
GTasks HD is a task manager that syncs to the Google Tasks service, through a very simple and clean interface. It supports recurring tasks, alerts and is universal so you can keep your tasks in sync between devices. The app is free, but you need to make an in-app purchase to get the full version. The free version supports two accounts, two lists and five tasks.
Price: Free
Developer: Yaniv Katan
Download: App Store
AirTodo
AirToDo combines a beautiful interface with Google Tasks syncing. It has lists, alerts, push notifications and you can attach location information, pictures and notes to each task. You can also backup (not sync) your To-Dos with iTunes File Sharing and Dropbox.
Price: $1.99
Developer: AllAboutApps
Download: App Store
Zero – To Do List
A very cool app and simple app, Zero – To Do List syncs with iCal or any calendar that supports the CalDAV format. You can add notes to your tasks, and the app can notify you of any tasks, including on your computer, since it syncs with iCal.
Price: Free
Developer: Functional Delights LLC
Download: App Store
Egretlist
Egretlist syncs your to-dos with Evernote in a beautiful and sleek interface. You can manage lists, notebooks, add images to tasks and even geotag them. You can share an Evernote account to collaborate on tasks, and creating new to-dos is very easy and quick.
Price: $2.99
Developer: MindsMomentum
Download: App Store
Droplist To Do
Syncs your To-Dos with Dropbox via text files. This is very simple and practical. It supports a variety of different formats, and you can even copy and paste lists from an email or the web and turn them into complete task lists. It’ll also remind you of any tasks due, and through the use of different lists, managing tasks with this app is a bliss!
Price: $2.99
Developer: Bloomingsoft
Download: App Store
Listary
Another clean and simple lists app, but this one syncs with Simplenote, a note service. It lets you manage your tasks in a simple way, and you can even share task lists through Simplenote.
Price: $2.99
Developer: Portmanteau
Download: App Store
Voodo – Easy Todo
Voodo lets you manage your tasks in an easy to use interface, giving you lots of options for configuration. Supports tags, search, quick task adding, local notifications and different view modes (like calendar, priority or nearby mode). It syncs your tasks with your Google Calendar account.
Price: $4.99
Developer: I Wonder Phone
Download: App Store
BusyToDo
BusyToDo allows you to manage your iCal/iCloud tasks easily. It supports recurring tasks, alarms, attaching URLs and locations to each task — and even supports location alarms. It’s compatible with the iPad too, so that’s a plus!
Price: $9.99
Developer: BusyCal LLC
Download: App Store
WillToDo
Through a simple interface, you can manage your tasks and sync them with Google Tasks. They are planning to add many more features in the future, but right now they support the basics, including task alarms.
Price: $0.99
Developer: Colorful Logic
Download: App Store
iProcrastinate
This is a pretty well known task management app. It syncs to its Mac companion (available through the Mac App Store) and Dropbox. It supports different lists, recurring tasks, breaking complex tasks into steps and many other features.
Price: $0.99
Developer: Craig Otis
Download: App Store
NotifyMe
This one is awesome. It syncs with its iPad and Mac companion apps (and even has a web interface). Very useful, although the rest of the apps are sold separately. Supports recurring reminders, notes, categorization as well as local and push notifications for each reminder.
Price: $3.99
Developer: PoweryBase Inc.
Download: App Store
File Management & Productivity
Dropbox
If you don’t know Dropbox, well, you’ve been missing quite a service! This iPhone app will give you access to your Dropbox account, and even let you upload files right from your phone, manage and sort them, and even store them on you device for offline viewing.
Price: Free
Developer: Dropbox
Download: App Store
Air Sharing Pro
Air Sharing Pro allows you to access a vast amount of file storage services, including Dropbox, Google Docs, iDisk and even FTP and SFTP servers! It’s a very powerful app, it supports a variety of different formats — you can even print documents right from within the app.
Price: $6.99
Developer: Avatron Software, Inc.
Download: App Store
Pastebot
Pastebot is a clipboard manager that syncs with your Mac, allowing you to copy something on your desktop and have it available on your iPhone instantly. It boasts a beautiful interface, and lets you manage text and image clippings, push text and images instantly to your mac, and more.
Price: $3.99
Developer: Tapbots
Download: App Store
Note Taking
Elements
This is a great app for writing. You can use markdown to format your notes and it syncs them all with Dropbox. Considering its beautiful interface and the fact that it’s universal (it works on the iPad too), it makes it a great choice for people who love writing.
Price: $4.99
Developer: Second Gear
Download: App Store
Write 2
Another app for writing, which has the ability to create notes, lists, has PIN protection, PDF exporting, word and character count, and you can even customize the app with themes. It syncs with Dropbox, so you have your notes available wherever you are.
Price: $1.99
Developer: Daniel V.W
Download: App Store
Notes+
This app allows you to take notes and then sync them with your Mac or PC via WiFi, once you’ve installed the provided syncing application to your computer. You can categorize, filter and search notes, and even hide important ones, which can later be seen by entering a password.
Price: $1.99
Developer: SEPV CORPORATION
Download: App Store
MomoNote
This is a very cool app. It works on both the iPhone and the iPad, and syncs to the web through MomoNote’s service. You can attach pictures, search, share and lock your notes. It also supports “Smart Lists,” which work very much like iTunes’ smart playlists by defining search terms.
Price: $4.99
Developer: MK HQ
Download: App Store
NoteMaster
This lets you create notes and sync them with Google Docs. It has a very nice interface and even lets you add images to your notes. It supports categories (which can be password protected) and you can send notes through email with rich HTML formatting.
Price: $3.99
Developer: Kabuki Vision, LLC
Download: App Store
PlainText
This app works with both the iPhone and the iPad, and syncs your notes to Dropbox. It doesn’t let you style your notes that much, but you can organize them into folders and it’s paper-like interface keeps you focused on the text. Ads can be removed through an in-app purchase.
Price: Free
Developer: Hog Bay Software
Download: App Store
Simplenote
This is a great app that lets you write notes and then categorize them with tags. It’s universal (works on the iPad too), and syncs with all your devices, including a lot of services detailed on the app’s website (and even some apps, which are detailed in this article).
Price: Free
Developer: Codality
Download: App Store
Notesy
Notesy is another note-taking app that syncs with Dropbox. It has many features such as built-in searching (including regular expression support), full offline and TextExpander support.
Price: $4.99
Developer: David Findlay
Download: App Store
Notely
This note-taking app syncs with Dropbox automatically. Plus it supports Markdown formatting, which is a plus, and it works on the iPad too. You can manage your notes with folders, printing, emailing notes inline or as attachments, autosave, and a lot more.
Price: $3.99
Developer: Magoaten
Download: App Store
Finance
Toshl Finance
Toshl Finance helps you keep track of your expenses in a beautiful interface. It syncs to the Toshl website, where you can get a better look at where your money is going. You can manage your expenses using tags, multiple budgets (although this feature is paid), and export your data to different formats.
Price: Free
Developer: 3fs
Download: App Store
HomeBudget
A very complete budgeting app, it lets you sync multiple devices so you can keep track of your whole family expenses. It supports recurring expenses, photo attachments, different categories budgets and accounts, etc. Plus, it works on the iPad.
Price: $4.99
Developer: Anishu, Inc.
Download: App Store
News
Reeder
It’s a Google Reader client (so it syncs with the service), and it can save posts to Evernote, Instapaper, ReadItLater and others. It also supports shared and starred items, folders and notes.
Price: $2.99
Developer: Silvio Rizzi
Download: App Store
Instapaper
Instapaper lets you save web pages for offline reading. This app works on both iPhone and iPad, and syncs with the Instapaper service which can be used from a variety of devices. Its beautiful and simple interface makes it great for reading all your offline articles and pages, plus the interface is customizable, so you can change background color, fonts and sizes, etc.
Price: $4.99
Developer: Marco Arment
Download: App Store
Read It Later Pro
Read it later lets you save web pages to, well, read them later. It works on the iPad too, and syncs to many platforms, just like Instapaper. It also has a great interface, so reading articles with this app is simple, allowing you to customize fonts, sizes and colors.
Price: $2.99
Developer: Idea Shower
Download: App Store
GoReader
GoReader is another RSS reading app. It features a very nice interface and syncs with Google Reader. It allows you to manage your RSS feeds with ease, share them and even customize font sizes.
Price: $4.99
Developer: Light Room
Download: App Store
Calendars
GooCal
GooCal syncs with your Google Calendar account to make it easy to manage your appointments. It supports multiple calendars and accounts, full bi-directional syncing and event search.
Price: Free
Developer: Developer Name
Download: App Store
gCalendar
This app also syncs with your Google Calendar account, with a very simple interface. It supports multiple calendars and a maximum of 1000 events.
Price: $2.99
Developer: Takashi Wada
Download: App Store
CCal
This is a very complete calendar app. It syncs with your Google Calendar account, works on the iPhone and iPad, lets you copy and paste events, arrange events using drag and drop, and even attach pictures.
Price: $5.99
Developer: Catalystwo Limited
Download: App Store
Vertical Calendar
Vertical Calendar has a unique approach to showing your appointments. You can view your entire month on a single page, and you can even create custom wallpapers so you can see your appointments from your lock screen. It syncs with your iPhone’s calendars and Google Calendar account.
Price: $1.99
Developer: Unitac
Download: App Store
Pocket Calendar
Pocket Calendar is a great app that syncs with Google Calendar. It has a very nice interface, and all the functionality one would need from a calendar app. It also supports 1- or 2-way syncing, landscape week view and quick event creating.
Price: $1.99
Developer: BlueTags
Download: App Store
iStudiez Pro
This app is a must-have if you’re a student. It tracks your schedule, assignments, tests, and more. It works on the iPad and on the Mac as well, and syncs everything between those devices. It boasts a beautiful and clean interface, supports alerts and you can even track your grades and GPA.
Price: $2.99
Developer: iStudiez Team
Download: App Store
Browsers
Sleipnir Mobile
Sleipnir is an alternative to Safari for the iPhone and the iPad. It syncs its bookmarks through its own service on all your devices. Its main feature is the way it handles tabs, with a unique interface. A must-try!
Price: Free
Developer: Fenrir Inc.
Download: App Store
Firefox Home
This is a very useful app if you use Firefox on your desktop. It syncs all your bookmarks and open tabs between your iPhone and your Firefox browser, seamlessly and easily.
Price: Free
Developer: Mozilla
Download: App Store
Do You Know Any Other Apps That Sync?
I tried to include most of the apps that provide some syncing functionality in this article. You probably already use at least one of these, but if you know any other app that I might have forgotten, please tell us in the comments!