Substack helps writers build paid newsletter subscription businesses in exchange for a commission of 10% plus Stripe's payment processing fee. The platform includes a dedicated discovery section that ranks top newsletters as well as a newsletter of its own and a podcast. Substack’s co-founders, Hamish McKenzie, Chris Best, and Jairaj Sethi, were named Adweek’s Publishing Executives of the Year in 2020.

Substack reported than 500,000 paid subscribers as of March 2021, with at least 10 writers earning more than USD 1 million per year. The company's “Substack Pro” product offers up to USD 250,000 or more to select writers for their first year on the platform in exchange for 85% of the writers’ subscription revenue.

In March 2021, the company responded to complaints that it had offered Substack Pro deals to transphobic and right-wing writers by clarifying its content moderation policies against harassment and hate speech. Substack also maintained “a hands-off philosophy when it comes to censorship,” and it has guidelines that “protect writers’ ability to openly express themselves while prohibiting harmful or illegal behavior," and rejected the influence of public pressure campaigns on its decision making.

Also in March, Substack raised its USD 65 million Series B funding round led by return investor Andreessen Horowitz, valuing the company at approximately USD 650 million. Since then, Substack launched “Substack Local,” an initiative to support the local news ecosystem with USD 1 million in payments to 30 independent writers as well as mentorship and business support.

Earlier this year co-founder Hamish McKenzie met with Jun Morikawa, deputy editor-in-chief of NewsPicks—a sister company of SPEEDA Edge—to talk about how Substack got started and where its priorities lie going forward. This conversation has been edited for length and clarity and is presented here in English for the first time.