Top 7 API Security Testing Tools

Choosing the right API security testing tools depends on what stage of the testing lifecycle you are in and how much automation you need. Some tools are built for manual exploration -- great for pentesters who want granular control. Others are designed for automated scanning in CI/CD pipelines where speed and coverage matter more than interactive debugging.

This guide compares the best API security tools available today, covering their strengths, limitations, and pricing so you can build a testing stack that matches your workflow. If you want to understand the testing methodology these tools support, read our guide on how to test API security first.

1. Metric Tower -- Automated API Discovery + Vulnerability Scanning

Metric Tower takes a pipeline approach to API vulnerability scanning. Rather than offering a single tool, it chains multiple specialized scanners together: SwaggerJacker discovers API specifications and undocumented endpoints, Arjun finds hidden HTTP parameters, Nuclei runs template-based vulnerability checks, and the sensitive-files scanner detects exposed configuration files and credentials. All of these run automatically in a single scan, with results from each tool feeding into the next.

Pros

• Multi-tool pipeline catches what single-tool scanners miss
• API spec discovery is automatic -- no manual setup required
• Findings are deduplicated and tracked across scans, so you can see what's new and what's been fixed
• GraphQL auditing via dedicated module (introspection, batch query, DoS checks)
• CI/CD integration via REST API for automated pipeline testing
• JWT vulnerability scanning built into Nuclei templates

Cons

• Less interactive than Burp Suite for manual exploration and request modification
• BOLA/authorization logic testing still requires manual verification of results

Pricing

Free tier available with limited scans. Pro and Business tiers start with monthly credit allocations. See pricing page for current plans.

2. Burp Suite -- The Manual Testing Gold Standard

PortSwigger's Burp Suite has been the primary tool for professional API and web security testing for over a decade. Its intercepting proxy captures every HTTP request between client and server, letting you inspect, modify, and replay requests in real time. For API testing, the workflow is: proxy your API client's traffic, build a site map of all endpoints, then use the Repeater and Intruder tools to test individual requests for authorization flaws and injection vulnerabilities.

Pros

• Unmatched control for manual API exploration and request crafting
• Extensive extension ecosystem (AuthMatrix for authz testing, Autorize for BOLA, JWT Editor)
• Active scanner catches injection flaws with low false positive rates
• Intruder automates BOLA testing by iterating object IDs across endpoints
• OpenAPI/Swagger spec import to seed the scanner with known endpoints

Cons

• Steep learning curve for teams without pentest experience
• Community Edition lacks the active scanner -- the free version is proxy-only
• Not designed for CI/CD pipeline integration (Burp Suite Enterprise exists but is a separate product)
• Requires manual setup for each target and auth configuration

Pricing

Community Edition: free (no active scanner). Professional: $449/user/year. Enterprise: starts at $8,395/year for pipeline scanning (as of 2026).

3. Postman -- API Functional Testing with Security Scripts

Postman is primarily an API development and functional testing platform, but its scripting capabilities make it a capable tool for security-focused test collections. You can build collections that exercise every endpoint, chain requests together (create a resource, capture its ID, access it from a different account), and write test scripts that check for security conditions like missing rate-limit headers or unexpected data in responses.

Pros

• Excellent for building reusable API test collections that combine functional and security checks
• Request chaining makes it easy to test multi-step flows (auth, BOLA, data leakage)
• Collaboration features let teams share and version API test collections
• OpenAPI spec import auto-generates request templates for every endpoint
• Free tier is generous for individual use

Cons

• No built-in vulnerability scanning -- all security tests must be manually scripted
• No fuzzing, injection testing, or payload generation out of the box
• Tests only what you know to test -- no discovery of unknown endpoints
• Not a replacement for dedicated security tools for compliance requirements

Pricing

Free tier for up to 25 collection runs/month. Basic: $14/user/month. Professional: $29/user/month. Enterprise: custom pricing (as of 2026).

4. OWASP ZAP -- Free API Scanning with OpenAPI Support

OWASP ZAP (Zed Attack Proxy) is the most widely used free and open-source web security scanner. For API testing, ZAP can import OpenAPI/Swagger specifications and automatically generate requests for every documented endpoint, then run its active scanner against them. It supports both REST and SOAP APIs, and its API scan mode (via the zap-api-scan.py script) is designed for CI/CD integration.

Pros

• Completely free and open source
• Native OpenAPI/Swagger import for seeded scanning
• Docker image with dedicated API scan script for CI/CD
• Active community and regular updates
• Extensible via Python and JavaScript scripts

Cons

• Higher false positive rate than commercial tools -- requires manual triage
• No API spec discovery -- you must provide the spec manually
• Authentication configuration can be complex for token-based APIs
• Limited GraphQL support
• Slower than purpose-built tools for large API surfaces

Pricing

Free and open source. No paid tiers.

5. 42Crunch -- API Security Platform with OpenAPI Audit

42Crunch takes a spec-first approach to API security. Their core product audits your OpenAPI specification for security issues before you even deploy -- checking for missing authentication requirements, overly permissive schemas, and insecure defaults. They also offer a runtime scanner (Conformance Scan) that validates whether the deployed API matches its specification.

Pros

• Static analysis of OpenAPI specs catches design-level security issues early
• IDE plugins (VS Code, IntelliJ) provide inline security feedback as you write specs
• CI/CD integration for spec audit gates before deployment
• Conformance scanning verifies implementation matches the spec
• Detailed scoring and remediation guidance for each finding

Cons

• Requires well-maintained OpenAPI specs -- less useful for undocumented APIs
• No discovery capability for unknown endpoints
• Runtime scanning is limited compared to full active scanners
• Enterprise pricing can be steep for small teams

Pricing

Free tier for individual audit (up to 3 APIs). Professional and Enterprise tiers with custom pricing (as of 2026).

6. Salt Security -- Runtime API Protection with ML

Salt Security operates differently from the other tools on this list. Rather than scanning APIs during development or testing, Salt observes live API traffic in production and uses machine learning to detect anomalies, abuse patterns, and attack attempts in real time. It acts as an API security posture management platform that discovers your full API inventory from traffic analysis.

Pros

• Discovers shadow APIs from live traffic -- no spec or inventory required
• ML-based anomaly detection catches zero-day API abuse patterns
• Timeline view shows the full attack progression, not just individual requests
• Automatic sensitive data classification (PII, credentials, tokens in responses)
• Integrations with API gateways, WAFs, and SIEM platforms

Cons

• Runtime-only -- does not test APIs before deployment
• Requires traffic mirroring or agent deployment in production
• Enterprise-only pricing, not accessible for small teams or individual testers
• Detection-focused rather than prevention-focused

Pricing

Enterprise pricing only. Contact sales for quotes (as of 2026).

7. SoapUI / ReadyAPI -- SOAP and REST Testing

SmartBear's SoapUI has been in the API testing space since 2005, originally focused on SOAP/XML web services. The open-source SoapUI and its commercial counterpart ReadyAPI now support REST, GraphQL, and gRPC testing as well. For organizations with legacy SOAP APIs that still need security testing, SoapUI remains one of the few tools that handles WSDL-based services natively.

Pros

• Best-in-class SOAP/WSDL support -- critical for legacy enterprise APIs
• Comprehensive data-driven testing with parameterized test cases
• ReadyAPI adds security scanning, load testing, and service virtualization
• Supports REST, GraphQL, and gRPC alongside SOAP
• Open-source edition is functional for basic security checks

Cons

• Desktop application with a dated Java UI -- less polished than modern alternatives
• Security scanning is basic compared to dedicated tools
• ReadyAPI's licensing model is per-seat and expensive
• Community has shrunk as SOAP adoption declines

Pricing

SoapUI Open Source: free. ReadyAPI: starts at approximately $749/user/year for the base test module (as of 2026).

Choosing the Right API Security Tool Combination

No single tool covers the full API security testing lifecycle. Here is how to think about building your stack:

For automated pipeline coverage: Metric Tower or ZAP for automated scanning in CI/CD, with Postman for structured test collections. This combination covers discovery, injection testing, and regression tracking without requiring dedicated pentest expertise on the team.

For manual penetration testing: Burp Suite Professional remains the go-to. Pair it with Metric Tower or ZAP for broader automated coverage, and use Postman to build repeatable test suites.

For enterprise API programs: Combine Metric Tower for shift-left scanning, 42Crunch for spec-level governance, and Salt Security for runtime protection. This covers the full lifecycle from design through production.

Feature Comparison Table

Feature	Metric Tower	Burp Suite	Postman	ZAP	42Crunch	Salt	SoapUI
API discovery	Yes	Manual	No	No	No	Yes (traffic)	No
OpenAPI import	Yes	Yes	Yes	Yes	Yes	Yes	Yes
Active scanning	Yes	Yes (Pro)	No	Yes	Limited	No	ReadyAPI
CI/CD integration	API	Enterprise	CLI	Docker	IDE + CI	Agent	CLI
GraphQL support	Yes	Via extensions	Yes	Limited	No	Yes	Yes
Free tier	Yes	Limited	Yes	Full	Limited	No	Open source
SOAP/WSDL	No	Yes	Yes	Yes	No	Yes	Best

Final Thoughts

The "best" API security tool depends entirely on your context. If you need broad automated coverage with minimal setup, Metric Tower's scanner chain handles discovery through vulnerability detection in a single workflow. If you need deep manual control for pentest engagements, Burp Suite is irreplaceable. If you have a mature API program with well-maintained specs, 42Crunch adds valuable design-time security gates.

The one approach that consistently fails is relying on a single tool. APIs are complex, and the vulnerabilities that matter most (authorization flaws) are the hardest for any single tool to catch. Build a stack that covers automated discovery, automated injection testing, and manual authorization review.