Upchain Software Developer interview questions

I was contacted by a recruiter about this job offer and then had a brief phone interview. Upchain invited me to come see them at their office located 325 Front st location, great location but a quite distance from where I live. I've been asked to do go through their product and present the demo to CTO. Overall I found the product, Cloud/SaaS agile software, interesting. I found the CTO very knowledgeable and has asked many technical challenging questions