You might want to pay a little bit more attention to branding if you're going to try do this. That sounds like a weird strategy, so let me explain. Right now its just an interface, and someone can look at that and say "yeah, one of our guys can do that next week, so we'd rather not buy it." The more you work on branding, the less easy that becomes. Instead of just having an interface, you have the "X" interface. So when people talk about the interface, they'll be talking about the "X" interface. Everyone will know its connected to you, and what a good job it does. It makes it harder to steal when it has a name and identity.
As far as them 'stealing' your concept, many large companies do not want to spend their internal capital budget to build tools and would rather focus those resources on their 'core competency.' That means buying commercial tools can make more sense in their budgets than building something on their own. In fact, our product development got a boost from one internal R&D team who lost their budget, and asked us to take the code they had developed and build a product. Then they would buy it from us using their ample remaining tools budget.