What are some alternatives?
When comparing Protranslate and Smartling, you can also consider the following products
OneSky - Full Stack Localization Solution
Crowdin - Localize your product in a seamless way
Transifex - Transifex makes it easy to collect, translate and deliver digital content, web and mobile apps in multiple languages. Localization for agile teams.
Zanata - Homepage for Zanata translation software
Phrase.com - Translate your software better. Edit and share locale files online. Work with your translators or order professional translations for your localization project.
Poedit - Poedit translations editor. The best way to translate apps and sites.