Demostack announces $17.5M investment for demo building platform Demostack, an early-stage startup that wants to make it easy for companies to build software demos, announced $17.5 million in funding today. The company also announced it was coming out of stealth. That investment breaks down into a $13.5 million Series A led by Bessemer Venture Partners with help from GTM Fund and several individual investors. They also announced a $4 million seed from last December led by Amiti Ventures with participation from Operator Collective, Cerca Partners and a slew of individual investors. All the seed investors also participated in the A round, according to the company.