Crowdin - Localize your product in a seamless way
openDesktop.org - The website openDesktop.
POEditor - The translation and localization management platform that's easy to use *and* affordable!
SourceForge - The Complete Open-Source and Business Software Platform.
Lokalise - Localization tool for software developers. Web-based collaborative multi-platform editor, API/CLI, numerous plugins, iOS and Android SDK.
Freecode - Freecode (formerly known as Freshmeat) is one of the legit open source development platforms that will be the key for developers and programmers to have a streamlined process via having enhanced collaboration and coding leverages.