Inside Zscaler’s Zero Trust Revolution: How It’s Quietly Replacing Firewalls Worldwide

Zscaler is Leading a Multi-Year Infrastructure Replacement Cycle

For a long time, corporate security was built around firewalls, VPNs, MPLS networks, SD-WAN appliances, and branch routers. These systems are expensive to keep up—between hardware maintenance, software licenses, and constant upgrades—and they create headaches for remote and cloud-based users by slowing things down. Worse yet, they leave companies vulnerable to lateral attacks, where once an intruder gets in, they can easily move around the network. Now that so much work and data live in the cloud, businesses are starting to ask: why keep investing in a clunky, exposed, and costly security setup?

This is where Zscaler (ZS) steps in. Its Zero Trust Branch and Zero Trust Cloud solutions let companies toss out firewalls, routers, and SD-WAN devices at their branch offices. Instead, everything flows through the cloud-based Zscaler Zero Trust Exchange, which means no network is directly exposed and attackers can’t move sideways through systems. The result? Branch offices effectively "go dark" online, making them nearly invisible and dramatically reducing the chances of a breach. Unlike others who simply shift old firewall functions into the cloud, Zscaler has reimagined the entire architecture—cutting out network exposure entirely.

Early Indicators For Zscaler Thesis Playing Out

There are early signs this approach is catching on. More than 130 customers have already rolled out Zero Trust Branch, and interestingly, 57% of them are brand-new to Zscaler, not just upsells. The company is pushing hard to triple adoption of its Zero Trust solutions across all areas within the next year and a half.

From an investment perspective, the opportunity here is massive. As companies rip and replace old hardware like firewalls, SD-WANs, and branch routers, it could free up around $20–30 billion in security spending over the next three to five years. Zscaler, having gotten out ahead of this shift, looks better positioned than anyone else to grab a large piece of that pie. Every Zero Trust deal Zscaler lands doesn’t just add a customer—it locks in long-term revenue streams that could stretch five to ten years into the future.