Top 8 Web Security Scanners

A web security scanner automates the process of finding vulnerabilities in your web applications -- things like cross-site scripting (XSS), SQL injection, insecure headers, exposed secrets, and misconfigurations that manual code review might miss. The challenge is choosing the right one. Some scanners are free and open-source but require significant expertise to run. Others are fully managed but cost thousands per year. Some excel at specific vulnerability classes while others try to cover everything.

This comparison covers eight web security scanners that are worth evaluating in 2026, with honest assessments of where each one excels and where it falls short. Metric Tower is listed first because it is our product, followed by seven alternatives that we respect and compete with.

What to Look for in a Web Security Scanner

Before diving into the tools, here are the criteria that matter most when evaluating scanners:

• Detection coverage -- which vulnerability classes does it find? XSS, SQLi, SSRF, and misconfigurations are table stakes. Template injection, CORS issues, and header analysis separate good scanners from basic ones.
• False positive rate -- a scanner that reports 500 findings with 400 false positives creates more work than it saves. Precision matters as much as recall.
• Authentication support -- can it scan behind a login? Most real-world web applications require authentication, and a scanner that can only check the login page misses the majority of the attack surface.
• CI/CD integration -- can you run scans automatically on each deployment? Shift-left scanning catches vulnerabilities before they reach production.
• Reporting -- does it produce reports that developers can act on and compliance teams can accept?

1. Metric Tower

Metric Tower takes a different approach from single-tool scanners: it orchestrates 58 specialized security tools through a unified interface. Instead of running one scanner and hoping it catches everything, ' . config('app.name') . ' runs ZAP, Nuclei, Dalfox, Sqlmap, Wapiti, and dozens of other tools in a dependency-aware pipeline where each tool's output feeds into the next.

A full scan starts with reconnaissance (subdomain discovery, DNS resolution), moves through port scanning and web crawling, then executes vulnerability scanners against the discovered attack surface. The result is broader coverage than any single tool can provide.

Metric Tower also offers free public tools including a security header checker that grades your HTTP headers from A+ to F, and full vulnerability scanning with integrated uptime, SSL, and DNS monitoring.

Pros:

• 58 security tools orchestrated in a single scan pipeline
• Tools feed data to each other (e.g., crawled URLs are tested for XSS, SQLi, template injection)
• Free security header checker available without signup
• Built-in monitoring (uptime, SSL, DNS) alongside vulnerability scanning
• Finding deduplication and trend tracking across scans
• CI/CD integration via API
• Multi-format reporting (PDF, SARIF, CSV, JSON, Markdown)

Cons:

• Full scans with all modules take longer than single-tool scans
• The breadth of features means a steeper initial learning curve
• Self-hosted deployment required (no SaaS-only option yet)

Pricing: Free tier with credit-based scanning. Paid plans for higher volume. See pricing.

2. OWASP ZAP

ZAP (Zed Attack Proxy) is the most widely used free web security scanner. Maintained by the OWASP community, it functions as an intercepting proxy, passive scanner, and active scanner. It is well suited for both interactive testing and automated scanning in CI/CD pipelines.

ZAP's active scanner tests for XSS, SQL injection, path traversal, remote file inclusion, and dozens of other vulnerability classes. The AJAX spider handles JavaScript-heavy single-page applications.

Pros:

• Completely free and open source (Apache 2.0)
• Active community with regular updates
• Excellent CI/CD integration (GitHub Actions, Jenkins, GitLab CI)
• Extensible via add-ons and scripts
• Good documentation and community support
• Automation framework for headless scanning

Cons:

• Can be noisy -- higher false positive rate than commercial tools
• Active scanning is slow on large applications
• Authentication configuration is complex (especially for modern OAuth/OIDC flows)
• No built-in template-based scanning (unlike Nuclei)
• Limited network-layer scanning (HTTP/HTTPS only)
• Requires expertise to interpret results and tune scans effectively

Pricing: Free. Open source.

3. Burp Suite

Burp Suite by PortSwigger is the industry standard for manual web application penetration testing. The Professional edition adds an automated scanner widely regarded as having one of the best detection engines available.

Burp excels at interactive testing: intercepting requests, modifying parameters, replaying requests, and exploring application logic manually. The scanner complements this workflow by automatically testing the endpoints you discover during manual exploration.

Pros:

• Industry-leading detection engine with low false positive rate
• Best-in-class intercepting proxy for manual testing
• Rich extension ecosystem (BApp Store)
• Excellent for testing complex authentication and business logic
• Burp Suite Enterprise for CI/CD integration
• Comprehensive training materials (PortSwigger Web Security Academy)

Cons:

• Professional edition costs $449/year per user -- expensive for teams
• Enterprise edition pricing is significantly higher
• Primarily a manual testing tool -- automation is secondary
• Steep learning curve for effective use
• Community edition is severely limited (no scanner, no saving state)
• Java-based, can be resource-heavy

Pricing: Community edition: free (no scanner). Professional: $449/year. Enterprise: contact sales.

4. Acunetix (Invicti)

Acunetix, now part of Invicti Security, is a commercial DAST scanner focused on compliance and developer workflows. It tests for over 7,000 vulnerabilities and is known for strong out-of-the-box detection of SQL injection, XSS, and OWASP Top 10 issues.

Acunetix's primary market is compliance-driven organizations that need automated scanning reports for PCI DSS, HIPAA, or SOC 2 audits.

Pros:

• Strong automated detection engine with good accuracy
• Built-in compliance reporting (PCI DSS, OWASP Top 10, HIPAA)
• DeepScan technology for JavaScript-heavy applications
• Good API scanning capabilities
• Integration with issue trackers (Jira, Azure DevOps, GitHub)
• Continuous scanning with scheduled scans

Cons:

• Expensive -- pricing is not public, requires a sales conversation
• Closed source with no community edition
• Less flexible than open-source tools for custom testing
• Limited network-layer scanning (web-focused only)
• Can be slow on very large applications

Pricing: Contact sales. Typically starts at several thousand dollars per year.

5. Nuclei

Nuclei by ProjectDiscovery is a template-based vulnerability scanner that has rapidly become one of the most popular tools in the security community. It uses YAML templates that describe how to detect specific vulnerabilities -- and the community has contributed over 11,000 templates covering known CVEs, misconfigurations, exposed panels, and default credentials.

Nuclei's strength is breadth: it can check for thousands of known issues very quickly. Its weakness is depth: it does not perform the kind of exploratory fuzzing that ZAP or Burp do. It checks for things you already know about, not things you do not.

Pros:

• Free, open source (MIT license)
• Over 11,000 community-maintained detection templates
• Extremely fast -- can check thousands of targets in minutes
• Easy to write custom templates in YAML
• Excellent CI/CD integration
• Active development and community (ProjectDiscovery)
• Low false positive rate (templates are precise)

Cons:

• Does not discover unknown vulnerabilities (only checks for known patterns)
• No interactive testing or crawling (pair with a crawler like Katana)
• Template quality varies -- some community templates are low quality
• No GUI (command-line only, though ProjectDiscovery Cloud adds a UI)
• Requires careful template selection to avoid overwhelming targets

Pricing: Free (CLI). ProjectDiscovery Cloud (managed platform) has paid tiers.

6. Nikto

Nikto is a legacy web server scanner that checks for dangerous files, outdated server software, and common misconfigurations. It has been around since 2001 and remains useful for quick checks, though it has been largely surpassed by more modern tools.

Nikto's strength is speed: it can check a web server for thousands of known issues in under a minute. It is particularly good at finding default installations, exposed admin panels, and server version disclosure.

Pros:

• Free and open source
• Very fast for basic server checks
• Good at finding server misconfigurations and default files
• Simple to run -- single command, no complex setup
• Wide database of known issues (6,700+ checks)

Cons:

• Very noisy -- generates many requests, easy to detect
• High false positive rate
• No JavaScript rendering or SPA support
• Limited to web server checks (does not test application logic)
• Infrequent updates compared to Nuclei
• No authentication support for scanning behind logins

Pricing: Free. Open source.

7. Wapiti

Wapiti is an open-source web application vulnerability scanner that takes a black-box approach: it crawls the application, discovers forms and parameters, then fuzzes each one to test for XSS, SQL injection, file inclusion, command injection, SSRF, and more.

Wapiti occupies a useful middle ground between ZAP and Nuclei. It is a straightforward automated scanner that you point at a URL and let run.

Pros:

• Free and open source (GPL)
• Black-box scanning requires no source code access
• Good detection for XSS, SQLi, file inclusion, and command injection
• Supports authentication (cookies, forms)
• Active development with regular releases
• HTML, JSON, and XML report output

Cons:

• Slower than Nuclei (it fuzzes parameters, not just checks templates)
• CLI only -- no graphical interface
• Smaller community and ecosystem compared to ZAP or Nuclei
• Limited JavaScript/SPA crawling
• Documentation can be sparse

Pricing: Free. Open source.

8. Qualys Web Application Scanning (WAS)

Qualys WAS is the enterprise-grade web application scanner from Qualys, a major player in the vulnerability management space. It is a cloud-based solution that integrates with the broader Qualys platform (VMDR, policy compliance, container security).

Qualys WAS is designed for large organizations needing centralized scanning across hundreds of web applications with compliance reporting, role-based access control, and integration with enterprise security workflows.

Pros:

• Enterprise-grade scalability (scan hundreds of apps from a central console)
• Strong compliance reporting (PCI DSS, OWASP, GDPR)
• Cloud-based -- no infrastructure to manage
• Integration with Qualys VMDR for unified vulnerability management
• Scheduled scanning with progressive crawling
• Good support and documentation for enterprise customers

Cons:

• Expensive -- enterprise pricing only, no self-service
• Slower detection updates compared to community-driven tools like Nuclei
• UI can feel heavy and enterprise-oriented
• Less effective than Burp for complex business logic testing
• Requires Qualys platform commitment
• Limited customization compared to open-source alternatives

Pricing: Contact Qualys sales. Enterprise pricing varies by number of web applications.

How to Choose a Web Security Scanner

The right scanner depends on your team's expertise, budget, and goals:

• Professional pen testers who do interactive testing daily should use Burp Suite. Nothing else matches its manual testing workflow.
• Development teams who want automated scanning in CI/CD should start with ZAP and Nuclei. Both are free, well-documented, and have strong GitHub Actions support.
• Security teams who want broad coverage without managing individual tools should look at Metric Tower, which orchestrates ZAP, Nuclei, and 50+ other tools in a single pipeline.
• Compliance-driven organizations that need audit-ready reports should evaluate Acunetix or Qualys WAS.
• Budget-conscious teams should start with the free tier at any of the open-source options (ZAP, Nuclei, Wapiti) and add commercial tools as needs grow.

Most mature security programs use multiple tools. ZAP and Nuclei for automated CI/CD checks, Burp for deep manual assessments, and a platform like Metric Tower for continuous monitoring. The tools are complementary, not mutually exclusive.

For a focused look at header-level security, check our guide on what HTTP security headers are and how to check and fix them.