Hello Aastha,
These are some :

• Allen
• Askiitians
• Aakashitutor
• kshitij-iitjee
• dreamjee
• EtoosIndia
• Iitjeeonline

And I suggestyou Etoosindia as I have found Etoosindia is providing one of the best online IITJEE coaching. Students can free download complete study material. IIT JEEquestion Papers, Sample papers, mock test series and video lectures areavailable on the site for free download. Take the best IIT JEE main free online coaching atfree.
I hope it will help you
Good luck..

These days, a lot of apps and videos are in feature for preparation of JEE MAins and Advanced. But do not rely on the too much. Only clear those doubts which you are unable to clear on your own by solving few questions.
Most popular ones are Unacademy, Vedantu, TopperLearning, Youtube videos by people like PhysicsWallah