Occasional faxers will appreciate Fax.Plus, which lets you send and receive 100 faxes a month for less than $6. MetroFax also supports a wide variety of file formats, and it's priced more attractively than a better-known online fax service like eFax. We think MetroFax is the best online fax service, offering a combination of fax-management features and easy-to-use software that appeals to frequent faxers. Here are the best online fax services - both free and paid - that we've found. We've tested many different companies over the years, returning to review old favorites that we've previously rated just to make sure they're still up to snuff. Here are the best PDF editors for creating documents.The best cable modems for staying connected.The good news is that several of the best online fax services we've looked at offer both free options and paid services. The former is good for one-and-done faxing, while the latter usually covers more extensive needs. You've got two options when you search for an online fax service - use one of the free tiers or sign up for a service plan.