iPhone App Localization: How To Get 767% More Downloads By Localizing App Keywords - This article provides information that will help you successfully market your app to foreign markets. Since the majority of apps are not localized, you can gain a huge advantage by ranking well on App Stores in foreign countries.

OneSky - OneSky's professional translators will localize your app's title, keyword, and app description at $0.10/word. If you keep your app description under 3-4 sentences, you can probably translate your app's data to 8-10 languages for $100. One Sky put together this list of statistics to prove why translating can be the most effective marketing decision you make. 

SensorTower - As a free service, SensorTower translates your app's keywords into all of the languages offered on the App Store.

Unbabel - If you are on a tight budget, Unbabel can translate for about $0.03/word. Unbabel runs your text through Google Translate and then has translators tweak the output to make sure there are no mistakes. Fluent multi-linguists have reported to us that the output from Unbabel is sometimes awkward compared to the translations by OneSky, so you may benefit by hiring OneSky if your budget allows.