If you are using trusted platforms like Upwork or Fiverr, it is quite impossible to get scammed as your payment is secured through a Escrow transaction. However, this does not mean freelancing sites are scam proof. I was once scammed on a Freelance market called Guru. I was hired to write a couple of articles, after I delivered my work, the employer vanished. That was during my early days of freelancing. Have you ever been scammed in a freelance market?
