"All" the live TV channels? No way that they're free. That includes both over-the-air (OTA) and pay-TV channels, and you're going to have to pay something to someone to get them "all."
The current live broadcasts on your local OTA stations are generally unavailable on the Internet or anywhere else, other than with an OTA antenna or in your pay-TV subscription.
As some of the other answers indicate, you *can* get a vast number of old TV programs and movies from various Internet resources, but you won't get the current episodes of major TV network series.
The cheapest option for quality HD television reception is a very good antenna, whatever is right for your particular location. That will get you your local OTA channels in the best HD available from any source other than a Blu-ray disk.
For anything more than that, you'll be paying something to someone, like an Internet provider fee and a subscription payment to something like Netflix.