Everyone talks about "granular SaaS control" like it's a solved problem. It's not. Both vendors claim they can do it, but the devil is in the *actual* policy construction and the apps they cover natively.
Having evaluated both:
* Prisma Access leans on its CASB integration. Good if you're already in that ecosystem, but the SaaS Security add-on is a separate SKU. Granularity often means another module, another cost.
* Zscaler's ZIA has broader native app definitions, but their "Business Applications" can get fuzzy. Controlling "Microsoft 365" is easy; isolating "Only Teams file uploads from SharePoint downloads" becomes a policy nightmare.
Key questions they don't answer upfront:
* How many SaaS app templates are truly "out-of-the-box" versus requiring custom URL definitions?
* What's the actual procedure to block a specific action (like file upload) in Salesforce but allow others? Is it a checkbox or a custom regex hunt?
* What additional fees apply for the CASB/DLP elements required for real control?
The marketing sheets look identical. The reality is a fight with policy layers and surprise add-ons.
Read the contract