The short answer is no. Not all employers are open to negotiation. However, once you receive an offer it is completely acceptable to ask if there is any room for negotiation. Even if the salary is non-negotiable, there are other benefits such as working from home, additional vacation days, flexible schedules, bonuses, and other benefits that may be negotiable. Keep that in mind and as long as you are polite and respectful, it is always reasonable to ask for a conversation about the offer.