I ran into the same trap! After trying a few disappointing ones, I checked out a detailed review on
akstrategic.com. They list apps that offer legitimate free tiers — some let you send a few pages per month without charges. I tested one of their suggestions, and it’s perfect for occasional use. Of course, if you fax often, it’s better to go for a low-cost plan, but for one-off faxes, their free picks are totally reliable.