1. A method for localization of a released computer program comprising: receiving, by a computer, a resource file for the released computer program that includes a first set of text strings in a base language that are used to display one or more text message on a graphical user interface during execution of the released computer program; receiving, by the computer, processing instructions that define a process for transforming the first set of text strings of the resource file into a first runtime resource file for the released computer program; receiving, by the computer, a second set of text strings in a target language, wherein the second set of text strings is platform-independent and comprises translations of the first set of text strings in the target language, wherein the second set of text strings corresponds to a valid International Organization for Standardization (ISO) language code and ISO country code that indicates the target language; determining, by the computer, changes made to at least one of the first set of text strings in the resource file after receiving the second set of text strings; translating, by the computer, the at least one text string into the target language; producing, by the computer, a second runtime resource file for the released computer program comprising the second set of text strings according to the received processing instructions that were used for transforming the first set of text strings of the resource file into the first runtime resource file for the released computer program; and executing, by the computer, the released computer program, wherein executing comprises loading the first runtime resource file and the second runtime resource file, receiving a language selection comprising a selection of either the base language or the target language, and displaying a text string from either the first set of text strings or the second set of text strings according to the received language selection.