Refactoring the Collectionsby Adam Wadden
Adam Wadden, a software engineer who also taught and made music, turned his frustration with poor PHP refactoring and testing resources into a self-published book and course, Refactoring the Collections. He built an email list and Twitter audience before a May launch with three pricing tiers, which made $25k on the first day and $65k in three days, and he then quit his job to build his next course. The source says he has done "two and a half million dollars in sales of his books and courses" since 2016.
Contentcontent-marketingone-timevia Indie Hackers Podcast