It might seem like there's a catch involved, but there isn't. There are many legitimate, free apps that allow you to make money by completing surveys, watching videos, secret shopping, sharing photos and more. Most of these apps offer modest pay and allow you the flexibility to earn money when your schedule permits.

Android and iOS users can earn gift cards, airline miles, magazine subscriptions and more for completing 15- to 20-minute surveys. After downloading the app, you'll tell the app a little about yourself to help iPoll match you to future surveys. Complete as few or as many questionnaires as you like, but the more you participate, the more you earn.