We are a Boston-Based Provider of Private Capital to Growing Businesses. Mainspring Capital is built upon decades of entrepreneurial and investing experience. We know what it takes to build a successful company, because we have been there. And we also understand that you're the expert in your business. What we do is fairly simple - whether you are an early stage venture looking for growth capital or a founder looking to exit, we can provide smart, flexible capital and the hands-on experience to help you achieve your goals.