I run Buttondown (http://buttondown.email/) full-time now, but did so as a side project from 2017 to earlier this year.
My strategy was fairly simple: I wanted to create a better version of a tool (in this case, Tinyletter) that:
1. I already used whose quality I thought was extremely poor,
2. I did not think the creators were incentivized to make improvements;
3. I could think of a sub-niche that I was well-equipped to build because it reflected my own experience (support for Markdown, a REST API — basically developer-adjacent functionality.) [^1]
I think we are in general pretty awash in bad products; it is not particularly difficult to pay attention to what you use over the course of a week and see what could use some obvious improvements.
[^1]: People often think of 'niching down' as adding features, but I would argue it is often just as much about removing features. As companies grow, they must add more and more surface area to satisfy certain use cases. Side projects do not have this problem; they can be laser focused on one or two such use cases, and as such remove all the surface area that many users find to be detritus.
The part about 'niching down' is really important in the side-projects world, and a lot of people are missing that.
They try to build all-in-one heavy projects, hoping to provide more values than existing products.
I higly agree with simplicity and decluterring projects to provide a real, but simple value.
I tweeted and wrote a fair deal about the process, and had good-but-not-great launches on HN and Product Hunt. There was definitely no 'big bang' where one day I did not have product-market fit and/or traction and then the next day I did; it was a slow drip of new users and new customers who helped refine the product & its position.
This is a strong _advantage_ of having something be a side project; your runway is drastically longer than other business models. (For example, from 2017—2018 MRR slowly grew from around $500 to around $1500. This slow growth felt painful, but also it was incredibly sustainable since I wasn't drawing a salary from it; churn was extremely low, and the only real problem was a small top-of-funnel since I wasn't going viral or spending money on ads.
I'm going to answer for op here and point out the product exponentially self-advertises. As more people send emails using the app, even if there isn't a "Sent with Button-down" it's easy to find out the email-sender so customer's receiving the email think to themselves, I could do that, and use that nice product!
Interestingly, this is exactly how I found about Buttondown, which I've been using for years to send my own newsletter.
It also helped that it was priced way more sensibly than many alternatives, in a way that grows linearly with the number of subscribers (which is also how, theoretically, ads returns from a newsletter can grow): my then provider would meet me with a massive cliff-edge, going from $0 to about $30/month, if I recall correctly. It's a common behaviour – lock in first, then charge A LOT :)
Which makes me wonder – maybe a simple, overlooked way, to start side hustles is to replicate a service, but offer better pricing that works for niche/bootstrapped contributors, as opposed to creating niche versions of the service?
My strategy was fairly simple: I wanted to create a better version of a tool (in this case, Tinyletter) that:
1. I already used whose quality I thought was extremely poor,
2. I did not think the creators were incentivized to make improvements;
3. I could think of a sub-niche that I was well-equipped to build because it reflected my own experience (support for Markdown, a REST API — basically developer-adjacent functionality.) [^1]
I think we are in general pretty awash in bad products; it is not particularly difficult to pay attention to what you use over the course of a week and see what could use some obvious improvements.
[^1]: People often think of 'niching down' as adding features, but I would argue it is often just as much about removing features. As companies grow, they must add more and more surface area to satisfy certain use cases. Side projects do not have this problem; they can be laser focused on one or two such use cases, and as such remove all the surface area that many users find to be detritus.