EDIT August 2021: Here is the project https://textspot.io/
In April of 2019, I built a stupid simple no-code SMS scheduling web app in less than 10 hours that is now making over $500/month.
It happened after my wife complained about not being able to find a simple, free application online that would allow her to schedule a hand full of text messages as reminders for a work project.
I got curious and decided to try to build it myself without code (I know WordPress + plugins, and HTML & CSS really well and that's about it).
Almost 2 years later and maybe an hour or two a month of SEO work, I have over 4,500 accounts created.
The tech stack:
I run an SEO agency for a living, so I did a little strategic work around the domain name I purchased and the initial content I wrote.
We're now ranking on page 1 of Google for 157 keywords that:
After a few months of leaving it up, I started getting a sign-up or two a week.
Fast forward to Fall 2020 and I tested a simple paid version (pretty much just allowing you to send more texts because I was paying the Twilio fees for the free accounts, which are limited to 20 texts/month).
People started signing up for the paid accounts and we're now getting about 100 free account sign-ups per week.
Now I've got a couple of developer friends building a legitimate web app and I'm excited to continue to share the story of how it goes right here.
We'll be re-launching the new platform and I'll be sharing the domain shortly.