I built an app plugin for Shopify called Custom Fields <a href="https://customfields.bonify.io" rel="nofollow">https://customfields.bonify.io</a><p>I must say, if you want to build something that instantly has a market consider building plugins for existing 3rd party systems that allow you to charge a fee. It ends up being a much smaller project than trying to build your own, huge web app, and it comes with a targeted, focused audience who can easily install your app with a couple clicks (and get charged). You don't really have to market anything.<p>Build something good and people will find it.
Semi-tangent: about 2 months ago someone posted a site that listed potential SaaS eligible services requested and suggested price points, does anyone recall that url?
<a href="http://indiehackers.com" rel="nofollow">http://indiehackers.com</a> is a great resource for learning about profitable side projects
Namevine: <a href="https://namevine.com/" rel="nofollow">https://namevine.com/</a><p>Find a domain name with matching social media handles. Instantly searches as-you-type. Also provides some simple "suggestions" based on common startup prefixes and suffixes.<p>Monetized via affiliate commissions on referred domain sales.
Selling Rsync/ZFS-Storage as a service at $.05 per GB - figured how to combine Cygwin Rsync and Volume Shadow Service on windows to backup locked files.
nothing to contribute on my own, but this may interest you: <a href="https://www.indiehackers.com/businesses" rel="nofollow">https://www.indiehackers.com/businesses</a> - probably something worth reading as it goes in to ideas and their implementation. interesting to note that there is a weather app chrome extension there that seems to make 2.5k per month.