The Intercept is the on-line magazine started by Glenn Greenwald, who is an English reporter who broke the Snowden story. If you watch the movie "Snowden" he is the male reporter that Snowden meets in Hong Kong. Greenwald was working for the U.K. based "Guardian", which is generally considered the most leftist of the British newspapers.
He left the Guaradian after the Snowdon affair, and started the Intercept. He also relocated to Brazil.
I think it would be fair to say that he is a leftist.
Strangely though his reporting on many issues is much more even handed than the US Press. He's recently written about the danger of the Trump Derangement Syndrome in the press, for instance.
His book "No Place To Hide" about the surveillance state is must reading on that topic.
Here is the bio he provides for himself at The Intercept.
Here is his Wikipedia bio Glenn Greenwald
Glenn Greenwald