Cloud security startup Wiz emerged from stealth with $100 million in Series A financing and a security platform already in use at Fortune 100 customers including Docusign.

The founding team, Assaf Rappaport, Ami Luttwak, Yinon Costica, and Roy Reznik, came from Microsoft’s Cloud Security Group and built the security stack for Azure. They’ve worked together for more than 15 years and also sold an earlier startup, cloud access security broker Adallom, to Microsoft for $320 million in 2015. The team left the cloud giant and started writing code for Wiz in January. Nine months later, Wiz has “dozens” of paying customers that use the company’s platform at scale, Wiz CEO Assaf Rappaport said.

“It was a tough choice to leave Microsoft,” he said. “Microsoft is an amazing company and one of the leading security providers in the world. Having said that, when you’re looking at a new problem, there is nothing like the agility of a startup to solve it. It was time to leave and start a company.”

And while Assaf’s earlier venture with Adallom ended in an acquisition, he sees a different path for Wiz. “We want to build a big company and take the company to IPO, which is quite different than the things we’ve done till today,” Assaf said.

The problem Wiz aims to solve is a biggie, though not unique: cloud security. And to do this, Assaf said his team takes a more wholistic, platform approach as opposed to using point tools to solve cloud security threats. Wiz’s product provides visibility across customers’ entire cloud environments. It scans all compute types and cloud services for vulnerabilities, configuration, network, and identity issues without agents or sidecars.

This unified approach reduces security teams’ alert fatigue and also simplifies customers’ IT environments while making them more secure, CTO Ami Luttwak said. Using one tool to scan for cloud misconfigurations, and another to find virtual machine (VM) vulnerabilities, and yet another to secure serverless and containerized application isn’t effective, he added.

“Our approach not only consolidates those products, it actually takes a different approach, how you should look at security,” Luttwak said. “You don’t want a mash up of all those different point solutions, you want to have one product that understands the entire environment. It has to be one solution that understands identity, and network, and vulnerabilities in VMs, and containers, and serverless, and really gives me that critical risk.”

Docusign is a public customer, and Assaf says Wiz has other financial companies and banks on its list, along with cloud-native technology companies. “It’s super highly regulated organizations, Fortune 100, banks that are just starting their journey to the cloud,” he said. “And at the same time born-in-the-cloud technology companies, so that’s the market opportunity available to us. It’s big, and it crosses multiple industries.”

The startup will use the Series A to grow its presence in the market and invest in research and development, Assaf said. “It’s all about innovation. Cloud is changing on a daily basis and getting more and more complex. We have the best product in the market, and we want to expand the gap we have.”

Index Ventures, Sequoia, Insight Partners, and Cyberstarts, led the $100 million funding round. In addition to the financing, Doug Leone, global managing partner at Sequoia Capital; Shardul Shah, partner at Index Ventures; Jeff Horing, managing director at Insight Partners; and Gili Raanan of Cyberstarts will join the Wiz board of directors.