Need to fax a document fast—what’s the best online fax service right now?

Hey guys, I urgently need to send a couple of legal documents via fax, but I don't have a traditional fax machine at home. I noticed there are tons of web services and mobile apps out there, but many have hidden fees or complicated subscriptions. Can anyone recommend a simple, secure online faxing tool that actually works well on both phone and desktop without any headache?