Dev & Engineering · Engineering, IT & AI
Should you build or buy DAST?
DAST (Dynamic Application Security Testing) software tests running web applications for vulnerabilities by simulating attacks — crawling the application, sending malicious inputs, and identifying exploitable weaknesses like XSS, CSRF, and injection flaws that only appear during execution.
The build-vs-buy decision for DAST turns on whether your AppSec engineering depth can absorb the operational overhead of running and maintaining a self-hosted scanner, and how much authenticated scanning and proof-based accuracy matter for your compliance program.
Build it, buy it, or bridge?
When building makes sense
Building a DAST program with OWASP ZAP is a real and deployed pattern — Docker-based ZAP baseline scans running in GitHub Actions against staging environments are documented standard practice at engineering teams that need dynamic security testing without enterprise contracts. Nuclei, which uses YAML-based templates, is another production OSS option for teams comfortable writing their own detection signatures. The case is strongest when your security posture requires testing infrastructure to stay on-premises, when your application footprint is small and well-understood, and when your team has AppSec engineering depth to maintain scan configurations over time. The limitation to price honestly: ZAP handles basic crawling and passive scanning well, but authenticated scanning across complex multi-step flows, session management, and API testing with proper context requires significant configuration work per application. Two to four weeks of setup per app, plus ongoing maintenance, plus the AppSec engineer time to triage findings — the total cost of a real ZAP-based program frequently approaches mid-tier commercial DAST licensing, removing the apparent cost advantage for teams without existing AppSec infrastructure.
When buying makes sense
Buying from Invicti, Rapid7 InsightAppSec, or Burp Suite Enterprise earns its keep when authenticated scanning, proof-based confirmation, and compliance reporting are the requirements. Authenticated scanning — testing the full application surface including protected pages and multi-step workflows — requires significant configuration effort to implement with ZAP, and commercial tools handle it with less per-app setup. Proof-based scanning, which confirms an exploit is actually exploitable rather than theoretically possible, directly reduces the triage burden that dominates AppSec team time. For compliance programs that need audit evidence, commercial tools generate the structured reporting that maps findings to OWASP Top 10 or PCI requirements with less manual assembly. The key insight from the economics: running a credible DAST program requires AppSec engineering time for triage and rule maintenance that frequently exceeds mid-tier vendor licensing costs regardless of which scanner does the crawling. The question isn't scanner cost; it's total program cost including the staff time to act on results.
The desk read
OWASP ZAP has been running in production CI/CD pipelines at real engineering teams long enough to be considered a standard tool, not an experiment. Docker-based deployment, GitHub Actions integration, and automated baseline scans against staging environments are all well-documented patterns. For teams that need dynamic security testing without an enterprise contract, ZAP and Nuclei cover the functional requirement.
The buy case for tools like Invicti, Rapid7 InsightAppSec, or Burp Suite Enterprise is strongest when you need authenticated scanning across complex multi-step flows, proof-based confirmation that reduces false positives, or integrated reporting for a compliance program. Those capabilities take real engineering effort to approximate. The economics are also less favorable to building than they appear: running a credible DAST program requires AppSec engineering time for triage and rule maintenance that often exceeds mid-tier vendor licensing costs, regardless of which scanner does the crawling.
Vendors in DAST
Each file covers what the product is, its funding history, and when the index last verified it alive.
Frequently asked
What is DAST?
DAST software tests running web applications for vulnerabilities by simulating attacks — crawling the application, sending malicious inputs, and identifying exploitable weaknesses like XSS, CSRF, and injection flaws that only appear during execution.
When does building DAST make sense?
Self-hosting OWASP ZAP makes sense for teams with AppSec engineering staff, on-prem requirements, and small application footprints where per-app configuration effort is manageable — though total program cost including staff time often narrows the apparent cost advantage.
When does buying DAST make sense?
Buying makes sense when authenticated scanning across complex flows, proof-based false-positive reduction, and compliance-ready reporting matter — commercial tools handle these better out of the box, and AppSec staff time for triage frequently exceeds mid-tier licensing costs anyway.
What are the main DAST vendors?
Representative vendors include OWASP ZAP, Invicti (Acunetix), Rapid7 InsightAppSec, Qualys WAS. B4 Pro scores the full set.