Keeping in mind these were a while ago, times have changed:
* A scraper and search engine that aggregated digital agencies by the technologies they were known to work with.
* A store locator, I had been seeing the request a lot on eCommerce stores and thought it would make a great SaaS. I was right about that, but unfortunately it wasn't mine that was succesful.
* An API dashboard tool that let you pick and display arbitrary data from any API endpoints you had access to. They were fetched and updated from the client's browser in real time, using a few different auth methods configurable by the user. It used an interface backed by JSON Path to let you select any part of the API's return value to display. I had hoped to go really far with the display UI, and allow for piping and manipulation of data before displaying it. But it didn't take off as an MVP.
* A page creator that used the concept of configurable blocks to build the page, this was way before Gutenberg and I feel like my approach to the UI was pretty novel even today. It was used almost exclusively for religious spam and I took it down because my country has no safe harbour laws, so I was potentially responsible for anything put up.
A bunch of others that never actually launched as well, including a management tool for mechanic workshops, a motorsport app to help manage a small DIY motorsport program, even a budgeting tool for long term travellers/nomads.