WebTranslateIt is described as 'A simple way to translate software. Software translation and project management in one platform'. There are three alternatives to WebTranslateIt for a variety of platforms, including Linux, Mac, Windows, Wordpress and Self-Hosted solutions. The best alternative is Okapi Framework, which is both free and Open Source. Other great apps like WebTranslateIt are Mojito (by Box) (Free, Open Source) and Loco Translate (Freemium).
Loco helps you manage and integrate translations into your software, whatever you're building. If you've ever experienced the nightmare of spreadsheets and emails that multi-language projects can bring, you'll understand why we built Loco.