All started back in 2011 when we were in search for an internationalization library that meets our demand - allowing to run both on server side Node.js and on our client side single page applications.
The first i18next landing page in 2011: http://i18next.github.io/i18next/
I18next was born and fastly grown to one of the most used frameworks for translating web applications and in Node.js. The response of the community was amazing and a fast growing ecosystem established itself around i18next.
With v2 of i18next, released in 2015, we completely rebuild i18next to be as extensible as possible.
Since v1 all newer releases can be dropped in as a replacement for v1 by just adding a minimal compatibility layer. The v1 API is still actively tested, here.
Shortly after the i18next v2 release in 2015, another big community driven i18next extension was released: react-i18next.