This study is based on the fact that the vocabulary mastery of seventh-grade students at SMPN 7 Satap Majene is still low. This was evident from the preliminary observations, in which students experienced difficulties in recalling word meanings and tended to feel bored with conventional learning media such as dictionaries. To address this problem, the present study aimed to improve students‟ vocabulary mastery through the use of the Memrise Web. This research employed a quantitative approach with a quasi-experimental design. The sampling
technique was random sampling, involving two seventh-grade classes at SMPN 7 Satap Majene as the experimental and control groups. The research instruments consisted of tests (pre-test and post-test) and a student perception questionnaire. The test was in the form of multiple-choice items, while the questionnaire measured students‟ perceptions. The findings revealed that the average pre-test score of the experimental class was 37.33, which increased to 80.00 in the posttest, while the control class only improved from 28.00 to 56.67. The average NGain score in the experimental class ranged from 0.3–<0.7 (medium category), whereas the control class only reached 29% (low category). The independent sample t-test showed a Sig. (2-tailed) value of 0.001 < 0.05, indicating a significant difference between the two classes. Moreover, the results of the students‟ perception questionnaire indicated that 3.99 of the responses fell into the highly perceived category. Therefore, the use of Memrise Web proved to be effective as an alternative learning medium that significantly improved students‟ vocabulary mastery.