The LG G3 comes with its own version of the stock Android browser, as well as Google's Chrome browser.
The stock browser packs the usual features: Incognito tabs, Bookmarks, Find in page and Desktop view. There is no Flash support. Pages can be saved locally to read offline, but videos cannot.
Google Chrome is becoming the most popular mobile browser and should be fairly familiar. It has some advantages over its vanilla-flavored buddy, including switching between tabs with a wide swipe from either the left or right of the top bar.
Thanks to your Google account, Chrome can sync what you have open on other devices (desktops, tablets) with the phone. This feature also syncs your bookmarks and favorite sites and can remember passwords and login data.
The Reduce data usage option sends web pages to be compressed on Google's web servers before loading them on the device to save data and speed up slow connections. This doesn't work for SSL-protected pages and Incognito tabs for privacy reasons.
LG's QMemo app, which was created as a response to Samsung's Notes application, is present on the G3 in the form of QMemo+. QMemo+ features a plethora of improvements, including the ability to add location and weather info to your notes, draw and add text to nearly any type of screenshot or picture, as well as share and save your notes via a wide range of media.
LG Health, LG's in-house fitness tracking app is also here, although it is only accessible as a part of the Smart Bulletin (i.e. the leftmost homescreen pane). LG Health is not as robust as Samsung's Health app (and the G3 doesn't have the same number of sensors for that purpose), but it does track various activities including walking, running, cycling, and more. You can create a LG account to compete with other LG Health users as well.
LG has re-skinned the Android Calendar app to match the Optimus UI design scheme. Adding an event lets you specify time (with a warning if there's a conflict with another event), attendees and location. Multiple online calendars are supported besides Google's.
The Tasks app is another way to organize time. It can handle multiple task lists and syncs with your Google account. Each task can have a due date and reminder associated with it.
Google Drive comes preinstalled. It combines all of your documents, spreadsheets, images and more in one easy to use data vault app. You can also access more than a single Google Drive if you have multiple profiles on your smartphone, which is neat.
The LG G3 also comes with a capable File manager application. You can either list all of the files of a certain type on your device, or browse the contents of your internal/expandable storage like on any other file manager. You can also integrate Dropbox cloud storage.
The Alarm clock application can handle multiple alarms, each with its own start and repeat time. The stopwatch and timer are self-explanatory. There's also a Calculator that displays advanced functions in landscape mode, and a Voice recorder.
Google Now, accessed by swiping up from any of the navigation buttons, integrates with your Google account and can access your daily routine, internet searches, email, etc. and give you information relevant to your interests and daily needs.
It provides traffic information to your work or home, knows the scores of sports teams you follow and gives you the weather forecast for your location. It's great for at-a-glance info, but can handle voice Google searches as well. It also has a dedicated homescreen/lockscreen widget.
Google Maps is the default navigation app, but it's most useful when used while you are online. It allows you to download offline maps of an area and even plan routes without a data connection but you can't search for addresses or POIs without an internet connection.
On the positive side, it can plan driving, public transport, cycling and walking routes. It can also display pretty accurate traffic alerts as well (though it doesn't always take them into account when routing you).
Another great support tool is the Android Device Manager. It's available for all Android devices linked to your Google account. It can help you find your misplaced LG G3 by ringing it or placing it on a map if it's not where you are. If it's stolen, you also have the option to lock the device and delete all data. You have to have enabled remote lock via the preinstalled Google Settings app on your smartphone.
And finally, Google's Play Store hardly needs any description. It the biggest catalog of apps and also features movies, TV, music and even devices but availability is region-dependent. Opening the store brings you highlighted apps based on recommendations and your usage. There are categories, ranked apps and more.
An important note is due here - the QHD screen means that not all apps will be compatible with the G3 from day 1. Some of those (including a few popular titles we stumbled upon) would need an update to make them compatible with the higher-res screens.