Yandex Blog

Yandex's Translation App for iPhone and iPad Now Provides Translations When Offline

Translation apps on mobile devices sure come in handy when you’re travelling to different countries where you don’t know the local language. But usually they use the internet to perform their translations, which means you need to go online to get help communicating with people or deciphering restaurant menus.

We have recently released an offline version of our Yandex.Translate mobile app for iPhone and iPad. So now this application can work without connecting to the internet, saving you the cost of internet roaming or the trouble of finding a wi-fi hotspot.


Yandex.Translate can be installed from App Store for free. After that, just go to the settings and choose the language pair or pairs that you need to translate to and from, and download the translation database onto your device. Five language pairs with English are available for offline translation: English-German, English-French, English-Italian, English-Spanish and English-Russian. If an English-speaking user is travelling from the UK to Spain, they’ll only need the English-Spanish offline translation database to get by day-to-day, while the other language pairs will only be available online (the app warns about this). After returning home to the UK, the user can delete the English-Spanish offline translation data to free up space.

While we’re on the subject of space and size, we really went to great lengths to get the balance right. As you might know, statistical machine translation is based on searching and indexing parallel texts on the internet. We look for already translated texts and phrases, compare them with the original and rank them according to how often they occur. You can read more about that here. These parallel texts, phrases and word combinations are quite cumbersome, taking up gigabytes on our servers.

For the translation app to work offline, we had to streamline the parallel translation database, so that only the most common translations remained. For example, if the full translation database gives 100 different ways to translate “where can I get the best tapas in Barcelona” into Spanish, the mobile version will retain only the 10 most commonly used translations.

We understand that this kind of streamlining can lower the quality of offline translations, and solving this problem was our biggest challenge. We ran a multitude of different tests and experiments to determine the optimal database size that would retain an acceptable translation quality for offline mobile gadgets. For every kind of translation, the optimal size turned out to be 500 MB. Larger (that is, with the addition of more translation variations) brings insignificant improvements to quality, even if the size is multiplied. And reducing the size and the number of translation options causes serious loss of quality without freeing up much space.

Yandex’s offline translation app can help users in daily life situations in foreign countries, whether they’re on vacation or a business trip: telling a taxi driver where to take them, comprehending what’s on a menu, understanding what street signs and warning signs say. These are the situations in which mobile translation apps are most often used. Our statistics also show that Yandex.Translate is used in private correspondence, school homework and university assignments, for reading tourism guides or news on the internet, for translating recipes, poems and songs. The average length of translations on mobile devices is five to seven words. At present, Yandex.Translate handles about 400,000 translations on mobile platforms every day. Most of our users are in Russia, but we are working on making the app popular outside our home country.

Since we first announced it in December 2012, the capabilities of mobile Yandex.Translate have grown enormously: it now “knows” 44 languages, offering a text-to-speech function for some – meaning it not only translates a phrase from your native language into a foreign one, but also lets you hear how it sounds when spoken.

Yandex challenges language barriers

Yandex has another go at language barriers to make life more comprehensible for iPhone users all over the world. Our Yandex.Translate app available for free in Apple App Store now has the English user interface. Yay!

The app, which was first rolled out in December 2012 with the Russian user interface was primarily designed for mobile users in the Russian-speaking countries and offered translations between Russian and eight languages including English, Ukrainian and Turkish. But with the brand-new English user interface and more languages now any speaker of English in the world with an iPhone in their pocket can read emails, newspaper articles, instructions, signs or even novels translated from French, Italian, Spanish, German, Turkish, Ukrainian or Czech. And, conversely, a speaker of any of these languages can use the Yandex.Translate app to have English texts translated for them into their language.

There’s no need to manually pick the right language for translation in the app’s settings – Yandex.Translate detects the source language automatically. A rare feat for mobile translators.

Together with announcing the English user interface, Yandex releases a Ukrainian version. The speakers of Russian or Ukrainian have historically had a bit more choice. For them, the app could translate words, sentences and entire texts between these two languages, as well as between either of them and English, Polish, German, French, Spanish, Italian, Czech, Bulgarian, Romanian, Serbian and Turkish.

The Yandex.Translate app for iPhone answered popular demand for mobility and followed our web-based translation service at first launched in March 2011 and used the same machine translation technology based on statistical regularities rather sets of rules.

Just like the web-based service, the Yandex.Translate app can translate words simultaneously – as you type them in the input field, and also offers suggestions for quick and flawless input, which is especially convenient when you are on the go. Predictive typing is indispensable on the mobile phone, when the user has to solve their typing tasks on a tiny screen and with a touch keyboard. Yandex.Translate is the only automated translation app that implemented a proprietary predictive text technology to offer its users a painless input experience.

When translating individual words, Yandex.Translate displays both the definition and the full dictionary entry including comments and usage examples.

In addition, using a text-to-speech technology the app can sound words in the entry titles for dictionary entries in Russian and Turkish when translating English words, and for dictionary entries in English, Italian, Spanish, German, French, Polish and Turkish if the source word is Russian. Not only can you learn the translation, but also hear what the word sounds like in one of these languages. Could score you points or get you out of trouble at some point. You never know.


While the app can only function on the internet-enabled iPhone, translation history is stored on the device and can be accessed while offline.

With over 150,000 downloads since its launch in December 2012, the Yandex.Translate app sees on average almost 40,000 downloads every month and serves over 15,000 users making more than 100,000 translations every day.

The majority of these translations – over 85% – are between Russian and English. Although right now 98% of all downloads come from Russia and Ukraine, of course, there is considerable interest from mobile users in the US, China, France, the UK and Israel, which will hopefully only grow now that we can offer our international users an international user interface.

The Yandex.Translate App for iPhone is available for a free download from the App Store and does not require a Yandex user account.