What Is Interactive Application Security Testing (IAST)?
Harness, Wednesday, September 30th, 2026
Harness explains how IAST instruments running applications to find vulnerabilities and where it fits in an AppSec program.
Harness explains Interactive Application Security Testing, which finds vulnerabilities in a running application by instrumenting its code and observing behavior during normal use or testing.
Unlike tools that scan code at rest or attack from outside, IAST watches data flow through the application in real time.
The article covers how IAST works, how it compares with other testing methods and where it fits in a modern application security program.