Smartphones, which have become a common, useful item in most parts of the world, are capable of greatly assisting traveler throughout the trip besides being used for communication purposes. Not only are they useful for planning the trip in advance, they can also be used during the trip to check up-to-date information while you are on the go, receive real-time updates, and they can also be used to solve various problems that might come up. Many smartphone apps are free, though some cost money, or certain services on the app may cost money.

Some of the most useful type of apps for travelers include:

• Instant messaging and VoIP apps - for keeping in touch with friends and family back home if you can't make ordinary calls or texts from the country you're visiting, and for calling and messaging people from other countries without paying exorbitant fees. Prominent apps in this category nowadays include WhatsApp, WeChat and Line.
• Real-time text translator apps - applications that are capable of automatically translating whole segments of text from one language into another. Some of the applications in this category can even translate texts in foreign languages on signs or other objects in the real world when the user points the smartphone towards those objects. The translation engines have improved dramatically, and now often give more or less correct translations (and more seldom gibberish), but some care is due, as they still may have gotten it all wrong. One of the most prominent apps in this category is Google Translate, which allows offline translation after downloading the desired language data.
• Real-time speech to speech translation apps - applications that allow two people, who speak different languages, ​​to communicate with each other through the application which recognizes the spoken words, and produces an audio output of the translated words so that both people can converse and understand each other. The apps in this category also aren't capable yet of producing completely accurate translations.

Before using these apps check you contract regarding international data roaming charges, these apps tend to transfer data continuously.

• Public transport apps - many national and regional rail and bus companies have their own useful apps that allow their customers to search for the ideal routes that will bring them to their destination, and/or to find information about timetables more easily. There are also apps that consolidate the public transit information of several cities into one app - an invaluable service if you are outside the area of public transit providers you normally use.

• Bike sharing locator apps - show where bicycles are available and where there are free slots to return the bike.

• Speed trap warning apps - these applications are capable of warning drivers when they are about to approach speed traps and/or of locations where traffic police might be waiting for people speeding. The apps with the latter feature usually relay on data provided by the app users. One of the most popular apps in this category is Waze. Blitzer.de (works in English and German) has fixed cameras in Europe and reliable for mobile cameras in Germany, as well as warnings of stationary traffic.

• Vehicle locator apps - these applications are especially useful to keep a memo of the exact location in which you parked your vehicle so that you'll be able to easily locate it later on (it can be especially useful if you have parked the vehicle in a very large parking lot or on the street of an unfamiliar bustling city).

• Map apps - Smartphones nowadays come with built-in GPS navigation and map applications, which can access detailed online maps of the entire world. One can also download additional map applications which are often free; some allow you to download detailed maps, making them useful also without internet access. The map applications can help you locate the hotels, businesses and attractions. Many map applications also provide traffic reports and are able to direct you through alternative routes in case of road traffic congestion. Some applications in this category can give warnings when speeding.
• Compass apps - many smartphones nowadays are capable of working as compasses using two or three built-in sensors. This solutions is not as robust as a traditional compass, but can be handy in some situations.
• The Wikivoyage app allows access to all Wikivoyage articles without an Internet connection.

• Camera and photo editing apps - Almost all smartphones nowadays include a built-in camera. This means there is no need to carry a separate camera, unless you need features not provided by the integrated one. Simple photo editing can be done with smartphone apps, allowing nearly immediate upload also when some fixes are needed. Still the power and better screen of an ordinary computer is an advantage if doing anything more complicated.
• Weather forecast apps - With smartphones one can get up-to-date weather information in the area you are currently at. Many weather applications are also able to provide fairly accurate weather forecasts for a specific hour in a specific day and use the GPS receiver of your mobile device to provide you with information relevant to your location at any time. There are also SMS services for the same purpose.
• Disaster alert apps - Countries exposed to natural disasters sometimes have an official app, for instance the Japanese governments offers an app that rings an alert as soon as an incoming earthquake is detected.
• Booking apps for flights / hotel rooms / car rental / etc - Many applications allow the users to search for airline tickets, hotels, car rentals, cruises, etc. The search results can usually be sorted by price. Airline and hotel chain specific apps can be useful for specific bookings, update of flight status
• Flashlight apps - many smartphones nowadays has this app as a built-in feature which turns on the backlight of the phone screen on full power, making the phone useful as a flash-light when needed.
• Apps for locating particular services in an unfamiliar city, such as WiFi hotspots or vegetarian restaurants.
• Rating and social badge collecting are apps for reviewing products and combined with recording your activities to collect points/badges. For example w:Untappd for beer enthusiasts.
• Banking apps let you monitor your balance, check for inflated fees, and transfer money if needed. Using a banking app on your own phone is usually more secure than logging in from an Internet café, though if it keeps you logged in, your banking information may be vulnerable if your phone is stolen. Please note that banks might ban entire countries from connecting to their website.

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