Is it illegal to have two full-time jobs?

No, it is not illegal to have two full-time jobs. You can technically work as many jobs as possible at any given time. You should consider if you have the time and energy to handle two full-time jobs before deciding to give it a go. You could try to add an additional part-time job, and then work up from there as you handle the additional hours.

While it is not illegal, it is important to understand potential legal implications that could arise if you do hold two full-time jobs, especially if they are similar positions in similar industries. Be sure to confirm that having an additional job does not violate any contracts or have any potential conflicts of interest with your current employer.