Hello buddy, there are many good  websites which provide online sample test/mock test for jee main. You can also get the mock test of coaching Institute.Jee official website also have mock tests.There are another website also for online tests:-

https://www.embibe.com/engineering/test

Best of luck for exam buddy. 

there are a lot of websites which provides the online support for the JEE examination. The JEE official website also hold a mock test platform and based on the expected pattern of questions. That site will also help you to prepare for the main examination. There are many other platforms for the online test.

https://www.embibe.com/engineering/test
This platform provides you good opportunity to test your skills free of cost.