Pros of JEE Mains Online Mode:

1. Candidates can choose their preferred timing and date of the exam according to the slots available as per convenience.
2. The restrictions of OMR Sheet: You can always change a marked answer in online mode. This freedom is lost in offline mode because, well, the ink is everlasting.
3. Assigning extra time for bubbling: Personally as a student, I would always have to keep extra ten minutes aside to colour the bubbles of OMR sheet. Of course, you cannot rush this process. On the contrary, online mode offers marking answers with one click!
4. Information like number of questions answered, number of questions unanswered, answers marked for review is available on the screen and in different colours.
5. The application fee in online mode is lower than paper and pen mode.
6. Students surely prefer an air conditioned room provided in online mode on a sweating summer afternoon. Perspiring improves concentration, said no soul ever!

Cons of JEE Mains Online Mode:

1. Technical glitches: These can occur anywhere and at most abrupt of times, especially in smaller towns with lesser technical expertise. If you feel that the facilities are not sufficient, you might want to sit this one out.
2. Question Paper is not given to students for further reference.
3. Looking at the computer screen for 3 hours could be strenuous for eyes.
4. Power cuts: A usual event in our country, not all facilities are provided with equipments to tackle power cuts. Why take a chance?

JEE Mains Offline Mode:

Pros of JEE Mains Offline Mode:

1. Reviewing the question paper: Students can go through the paper as per convenience. This helps them choose the section of their strength and begin with it.
2. No technical glitches or power failure fear: Since the examination is on paper, you couldn’t care less about the lack of equipped facilities or faculty.
3. Conventional: This mode is highly conventional owing to our education system, and hence students find it highly comfortable.
4. Students get to take the question paper for future reference.

Cons of JEE Mains Offline Mode:

1. Bubbling: The strenuous task of bubbling OMR, as mentioned earlier, eats up students’ crucial time which could have been used for revision. Also, it does not leave scope for correction of wrongly marked answer.
2. The application fee is more than online mode.
3. Students have to appear in the exam on allotted date and time