Is it allowed to work full-time while doing a Master's in the USA? 

Yes, it is allowed to work full-time while doing a master's degree in the USA, but it depends on the type of visa you have.

If you are an international student with an F-1 visa, you are allowed to work part-time on-campus (up to 20 hours per week) during the academic year and full-time during breaks (such as summer or winter break). You may also be eligible for off-campus employment through Curricular Practical Training (CPT) or Optional Practical Training (OPT) programs, which allow you to work in your field of study while you are still a student or after graduation. 

However, keep in mind that working full-time while pursuing a master's degree can be challenging and may affect your academic performance. It's important to balance your work and academic responsibilities and make sure you can manage both effectively.