What are some alternatives?
When comparing POEditor and Smartling, you can also consider the following products
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.
Poedit - Poedit translations editor. The best way to translate apps and sites.
Localize - Localize is translation software that automatically converts the content of your website or app into multiple languages.
Pootle - Multiple file formats.
Lokalise - Localization tool for software developers. Web-based collaborative multi-platform editor, API/CLI, numerous plugins, iOS and Android SDK.