I've been selling a couple of WordPress plugins since 2013, mostly piggy-backing on other popular services that were experiencing crazy growth and taking care of their WordPress integration for them (unofficially, some already had one that sucked).

Yearly (subscription) revenue is at about $500K USD now. It has been growing by less than 10% for the last few years as I haven't been that interested in growing it - I want to work less, not more.

So far I haven't seen any negative effects because of COVID-19 in terms of revenue. If anything there seems to be a slight uptick in new subscriptions and slightly fewer support emails per week.

- MC4WP: Mailchimp for WordPress: https://mc4wp.com/

- Boxzilla Plugin: https://boxzillaplugin.com/

- HTML Forms: https://htmlforms.io/