I’m part of a 20-person company that was in a similar situation. We have since built our software in-house, replacing the software we previously struggled with, and it’s worked out even better than I originally hoped because it felt so audacious at the time.
One thing I think is key is making sure that whoever is leading this project (the lead developer, not just the person they’re reporting to) needs to know the business cold. They should spend serious time learning the roles of the people who will be using the software so they can design it well to solve the problems those roles face. I lead the development for us, and I attribute most of the software’s success to simply having spent so much time in so many roles in the company. It’s that cross-section of knowledge that makes all the difference.
People often ask me about potentially selling software I’ve built for our company (a similar situation to OP), but one important factor to remember is that part of what makes the software great for us is its focus. As soon as you start selling it, you have to add feature after feature to meet the various customer needs, which then makes it worse for us. This may be a worthwhile trade off if the potential revenue is large enough, but it’s important to consider in advance.
One thing I think is key is making sure that whoever is leading this project (the lead developer, not just the person they’re reporting to) needs to know the business cold. They should spend serious time learning the roles of the people who will be using the software so they can design it well to solve the problems those roles face. I lead the development for us, and I attribute most of the software’s success to simply having spent so much time in so many roles in the company. It’s that cross-section of knowledge that makes all the difference.