In-app message (Rich Media) localization

Question: I added a second language (for example Japanese) to my in-app template for localization. After that the in-app is shown in that language to everyone, regardless of the language set on the device.

Answer: This is how the old Rich Media editor behaved: when the template had no language information yet and you edited the content for one language only, that language was written into the template's .json as the default, so every device got it.

In the current in-app editor (Content → In-apps) localization works differently and this situation should no longer occur:

• Use the language switcher above the canvas to add languages and edit the copy per language.
• Content you have not translated yet for the selected language is shown dimmed; start typing to create the translation. Until you do, the default language keeps being shown to those devices.
• Any new block you add appears with the same content in every language, so remember to translate new text and button labels for each language you use.

So the rule of thumb is unchanged: whenever you add a language, make sure the default language content is filled in as well. Devices whose language has no translation fall back to the default language, not to the language you happened to edit last.

If you upload your in-app as a custom HTML ZIP instead of using the built-in editor, localization is driven by the language files inside the archive — see the Rich Media templates syntax guide — and the same fallback rule applies: keep the default language populated.

See also: Multi-language messaging.