The live streaming rights to Thursday Night Football games are up for grabs.

The NFL is currently looking for a company to partner with for the upcoming season, according to a source familiar with the matter. Twitter (TWTR), Facebook (FB), Amazon (AMZN) and YouTube are among those in the running.

It won't be cheap for whoever gets the deal.

During the 2016-2017 season, the NFL partnered with Twitter, which livestreamed 10 TNF games. Twitter paid millions for the rights.

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The social media experiment was generally considered a hit with viewers, even if the numbers couldn't compare with how many people tuned into the game on TV.

For the first game, 243,000 people were watching during an average minute via Twitter (TWTR). By the same TV-style measurement, 15.4 million people were watching on CBS and the NFL Network.

Twitter's livestream of the first game reached a total of 2.1 million people. But that figure counts anyone who watched the game for at least three seconds.

The high-quality stream was easy to find on the Twitter app and users didn't report any major glitches.

Going into the 2017-2018 season, there will actually be a measurable comparison to determine the success of the livestreaming.

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The NFL is livestreaming games is to attract viewers who use social media and value mobility, as well as those who may not have cable.

Last year's stream was accessible in every country where Twitter operates, and presumably the same will be true if another company lands the deal. The one exception will likely be Canada, which has a different TV rights deal with the NFL.

Twitter, Facebook, Amazon and YouTube did not immediately respond to requests for comment.