Most software consulting vendors will not warrantee any and all damages to you and/or your customers who are using the custom software solution that the vendor is developing for you. It's important that you understand the limits of such liabilities and that you are comfortable with them before engaging the vendor. It is also common practice to limit the contractual liability to "the value of the delivered services or $X, whichever is greater", so that there is a limit to the financial impact of a failed project.