The day where you build an MVP software from scratch is over.
It used to cost upwards of $10k to start a SaaS. Most of the cost is labor-related - you pay for the engineering hours.
Not anymore.
These days, if your idea fits a pattern “X for X” targeting a new market vertical, most likely there’s open-source software for that. For example, airbnb for dog hotels, uber for medical transportation, etc.
Open-source software has been around for a long time. I remember the days of scouring good ones from sourceforge.net (it still stands!) and later the introduction of github.com. It makes going to market a lot faster!
There’s a catch - if your software isn’t novel, you will probably have trouble patenting it. Also, some license is more restrictive. The best practice is that you stick to using one with MIT license.
TO DO NOW
Take a look at this EXCELLENT list of ready use, open-source software at https://gourav.io/clone-wars