The English language, is one of the most widely spoken and influential languages in the world and precisely grammatical rules are one of the most challenging aspects of learning a new language. English as Second Language (ESL) learners are prone to making grammatical errors. In accordance to this, using various online quiz tools into grammar lessons, like as Kahoot!, Quizizz, and Wordwall.net, can increase intrinsic and extrinsic motivation among students, making the sessions more interesting and relevant. Thus, this research aims to investigate the effectiveness of various online quiz tools in enhancing the learning of grammar among ESL learners. A mix-method research design applying an action research model was used in this study. Instruments such as pre-test, post-test and semi-structured interview were used to collect the needed data. Research participants involved in this research were 30 pupils of Year 3 from a rural school in Semenyih, Selangor, Malaysia. The findings showed that various online quiz tools were very effective in enhancing the learning of grammar among ESL learners. The scores obtained by the learners in their post-test compared to the pre-test showed significant improvement. Moreover, the learners perceived the use of various online quiz tools in learning grammar in a positive manner. Therefore, it is hoped that this research would provide new information and serve as a guideline for teachers who want to create engaging activities in teaching grammar for young learners.