Localizing software applications into target languages such as French, Italian, Chinese, etc. is time consuming, expensive and error prone. End users often need to install and operate multiple copies of the same software applications localized into different languages if they need to work in multiple languages. By providing a localization engine with access to information about resources used in a user interface and translations of those resources, on the fly localization of software applications is possible. Context information is stored in the localization database and used to identify appropriate translations of the resources. Run-time context information is obtained from the user interface and/or software application and optionally a context information store. In some examples, target language resource results are presented in tooltip like displays. The translation information is stored in a localization database which in some examples comprises language-pair information whereby source language resources are stored in association with their translations.