Hi,

Here are some apps that I believe would prove helpful for any Gate Aspirant -

1. Made Easy. For Sure students praise a lot about their test series.

2. Unacademy.

3. Grade Up (Mostly proves good for any exam)

4. Engineering Circle (Good results for IES too)

5. The Gate Academy (New name in this field, but their reviews are pretty damn good)

Try all the apps yourself too. And make sure to read the reviews.

Hope this helps.

Good luck.