Strategies play an important role in learning a second or foreign language (L2). The aim of the current study was to develop and evaluate a co-sharing-based strategy learning system for L2 vocabulary learning known as "Mywordtools." Mywordtools is designed specifically for lexical learning, enabling learners to use the currently available vocabulary learning strategies (VLSs) as well as e-tools provided within this system to learn L2 vocabulary for both indoor and outdoor settings during learners' free time. The effects of Mywordtools on L2 learners' word learning were evaluated over a 5-week period. Sixty-one sixth-grade learners of English as a foreign language (EFL) participated in this study. The results of this study demonstrate that students using Mywordtools to practice and share VLSs outperformed both those who did not use Mywordtools and those who used the platform but without sharing. It was also found that strategy sharing helped L2 learners to construct more VLSs, and they consequently performed significantly better than those who did not implement strategy sharing. The overall results indicate that the use of co-sharing with Mywordtools not only benefits the development of VLSs by EFL students but also helps them to gain more in L2 vocabulary learning. (Contains 6 tables and 6 figures.)