An integration with payment processor OpenNode will allow content platform Substack to accept Bitcoin (BTC) payments on-chain and use the Lightning Network.

In a Monday announcement, OpenNode said it had partnered with Substack “to make it easy for writers and publications to get paid in Bitcoin.” According to OpenNode and Substack, the integration will only be available to “a select group of crypto-focused publications” on the platform.

The publishing platform, which allows writers to send their work directly to readers, has more than 500,000 paid subscribers, with the most popular writers reportedly earning more than six figures annually. The select Substack readers will be able to pay for their subscriptions in Bitcoin, with certain publications allowed to keep their earnings in crypto as well.

Substack product designer Nick Inzucch hinted that the platform could later expand its crypto payment offering to other writers in an effort to give them “more flexibility and freedom.” A number of prominent figures in the crypto space currently publish using Substack, including analyst Willy Woo and Kraken growth lead Dan Held.

Related: Second largest US mortgage lender will accept crypto payments this year

Founded in 2017, Substack is backed by venture capital firms Andreessen Horowitz, Y Combinator, Fifty Years and others. After a March funding round led by Andreessen Horowitz, the platform reportedly has a valuation of roughly $650 million.