A Cloud Access Security Broker sits between your users and the cloud services they use, enforcing your security policies. It gives you visibility into which cloud and SaaS apps are being used (including unsanctioned ones), protects the data in them, detects threats like compromised accounts, and helps you meet compliance. Think of it as a security checkpoint and control layer for all your cloud usage, rather than something that only guards your own network.

CASB capabilities are usually grouped into four pillars: Visibility (seeing which cloud apps are used and by whom, including shadow IT), Compliance (meeting data-protection and regulatory expectations), Data Security (cloud DLP and controlling how data is shared or downloaded) and Threat Protection (detecting compromised accounts, risky behaviour and cloud malware). A strong CASB covers all four; weaker ones are strong on one or two. We help you weigh which matter most for you.

API-based (out-of-band) mode connects to your sanctioned SaaS apps through their APIs — it can scan data at rest, sharing settings and configuration with no impact on performance, but it acts after the fact and only for apps it can connect to. Inline (proxy) mode sits in the traffic path and enforces policy in real time, covering unsanctioned apps and unmanaged devices, but needs more careful deployment. Many organisations use both — API for sanctioned apps and inline for real-time control. We help you compare CASB Services and choose the right deployment mix.

CASB is one of the core components of SASE/SSE, so you can buy it standalone or as part of a wider converged platform — we have a dedicated SASE comparison to help you decide. It's also related to but distinct from SSPM (SaaS Security Posture Management), which focuses on hardening the configuration of your SaaS apps; CASB focuses on access, data and threats in real use. Our SaaS Security Tools comparison covers SSPM in depth, and they often work together.

CASB helps you know where personal and sensitive data lives across your cloud apps, control how it's shared and demonstrate governance — directly supporting the DPDP Act, plus CERT-In, RBI and PCI expectations, with where data is inspected and stored mattering for residency. Pricing is typically per user per month, sometimes with separate costs for inline modes or managed delivery. Figures here are illustrative, and this is general guidance, not legal advice — confirm current requirements with the vendor and your advisors.