The Athletic, a sports-news subscription service launched in 2016, said it has reached more than 500,000 subscribers and expects to nearly double that total by the end of the year.

The site, which attracted 300,000 subscribers last year, crossed the half-million mark in June, said Alex Mather, co-founder and chief executive officer. "We'll end the year somewhere close to a million," he said.

The Athletic, based in San Francisco, is an ad-free, online-only network for local sports coverage. Subscriptions cost $10 a month or $60 a year, though many customers have signed up at lower promotional rates. The site's average annual revenue per subscriber is roughly $64, Mather said.

Since launching in Chicago three years ago, the Athletic has expanded to nearly 50 cities in the U.S. and Canada and hired hundreds of sports reporters and editors, often from local newspapers. It covers roughly 270 teams from the NFL, NBA, MLB, NHL and college sports.

The site is planning to introduce coverage of English Premier League soccer teams in August. Hiring in preparation for that launch has caused a stir in U.K. newsrooms.

Backers including Founders Fund and Comcast Ventures have driven the Athletic's rapid growth with more than $90 million in funding. The site has yet to show an overall profit but is profitable in all but a few markets, and new cities routinely achieve profitability within a year, Mather said.

The site is a test for the digital-subscription model in journalism. The New York Times, the market leader, counts 3.5 million subscribers, including its crossword and cooking apps.