FIRE

Most of the products don't make any revenue at all.
Success in the world of indie developers is an outlier business
Around 5 percent of the products we analyzed generate a monthly revenue exceeding USD 8,333 (around USD 100K/year), which is relatively easy to earn as a software engineer in a full-time job.

USD 14 million annual recurring revenue
No idea like this had existed, and the domain BuiltWith was somehow not taken already
For instance, certain pieces of code can be used to identify if Adsense is used vs. Adzerk or some other advertising method
AboutUs was an internet domain directory containing information about millions of businesses. Gary showed Ray BuiltWith, and Ray immediately loved it. He added a BuiltWith.com link to every record in their index to provide BuiltWith information regarding each business
This added tens of millions of links; for those who aren't SEO experts, backlinks (pages that link to your site) are the key to ranking high. And BuiltWith just exploded with traffic
BuiltWith's value comes down to a straightforward concept.
Competitive Advantage. Aka, you'll earn more money from this
BuiltWith has turned into a colossal database of everything on the internet
he realized one thing, BuiltWith didn't need this

Payment Infra for Software as a Service

Stripe Payments JavaScript Course
Stripe Atlas is a powerful, safe, easy-to-use platform for forming a company. Stripe Atlas helps you launch your startup from anywhere worldwide by removing lengthy paperwork, legal complexity, and numerous fees. - Stripe Atlas
Will go with Toss Payments Systems due to tax & governance issues