Top 24 Open Source Alternatives to OWASP ZAP

Introduction: Where OWASP ZAP Fits in Modern QA and Security

OWASP ZAP (Zed Attack Proxy) is one of the most widely used open source DAST (Dynamic Application Security Testing) tools. Originating from the OWASP community, ZAP matured into a practical, developer-friendly proxy that automatically scans web applications and APIs for security issues during runtime. Built in Java and licensed under Apache-2.0, it’s designed to be CI/CD-friendly, scriptable, and extensible via add-ons.

ZAP became popular because it made dynamic security testing accessible: it can passively and actively scan traffic, spider and crawl applications, test APIs, and fit into automated pipelines. Teams appreciate its strong community, solid documentation, and its suitability for security checks alongside functional test automation.

However, as software delivery becomes more polyglot and cross-platform—spanning web, APIs, mobile apps, microservices, and more—teams often need complementary or alternative tools. Some organizations seek broader test automation; others require deeper performance, accessibility, or API contract checks; and some want frameworks that integrate more naturally with their programming language or preferred test runner. This article explores open source alternatives that teams consider when looking beyond OWASP ZAP, either as replacements for parts of the workflow or as adjacent solutions that better match their priorities.

Overview: The Top 24 Alternatives Covered

Here are the top 24 open source alternatives (and complements) to OWASP ZAP:

• Appium

• Citrus

• EarlGrey

• Espresso

• Gauge

• Geb

• JMeter

• Karate

• Lighthouse CI

• PIT (Pitest)

• Paparazzi (Cash App)

• Playwright

• Playwright Test

• Puppeteer

• Rest Assured

• Robot Framework + SeleniumLibrary

• Selenide

• Selenium

• Shot (Kakao)

• Spock

• Stryker

• Taiko

• TestNG

• xUnit.net

Why Look for OWASP ZAP Alternatives?

Even though ZAP is well-established, teams often explore alternatives because:

• Narrow scope (web/API DAST): ZAP focuses on runtime web/API security. If you need mobile, desktop, or broader quality checks (performance, accessibility, mutation testing), you’ll likely need other tools.

• Specialized expertise: Effective DAST usage can require security know-how to configure scans, interpret findings, and reduce false positives.

• Reporting and triage: Out-of-the-box reporting may require customization or external integrations to meet enterprise vulnerability management workflows.

• Scaling and performance: Large, distributed systems can demand significant tuning to get comprehensive coverage within CI time constraints.

• Integration gaps: Security scanning often needs to slot into existing automation frameworks. Some teams prefer tools that live inside their language ecosystem or test runner with minimal glue code.

Detailed Breakdown of Alternatives

Below, each tool includes a brief description, core strengths, and how it compares to OWASP ZAP.

1) Appium

Appium is an open source mobile UI automation framework for iOS, Android, and mobile web. It enables cross-platform, end-to-end testing using the WebDriver protocol and boasts a large community and plugin ecosystem.

• Strengths:

• How it compares to OWASP ZAP:

• Platforms: Android, iOS, Mobile Web | License: Apache-2.0 | Primary tech: WebDriver

2) Citrus

Citrus is an integration and message-based test framework for HTTP, WebSocket, and JMS. It targets end-to-end testing of messaging and integration flows.

• Strengths:

• How it compares to OWASP ZAP:

• Platforms: HTTP/WS/JMS | License: Apache-2.0 | Primary tech: Java

3) EarlGrey

EarlGrey is an open source iOS UI testing framework from Google that integrates with Xcode and supports robust synchronization and interactions.

• Strengths:

• How it compares to OWASP ZAP:

• Platforms: iOS | License: Apache-2.0 | Primary tech: Objective‑C/Swift

4) Espresso

Espresso is Google’s official Android UI testing framework for writing reliable, fast UI tests that run on devices and emulators.

• Strengths:

• How it compares to OWASP ZAP:

• Platforms: Android | License: Apache-2.0 | Primary tech: Java/Kotlin

5) Gauge

Gauge, from ThoughtWorks, is a BDD-like test automation framework with human-readable specs and multi-language support.

• Strengths:

• How it compares to OWASP ZAP:

• Platforms: Web | License: Apache-2.0 | Primary tech: Multiple (JS/Java/C#)

6) Geb

Geb is a Groovy-based web automation DSL that pairs well with Spock and the JVM ecosystem to write clean, expressive UI tests.

• Strengths:

• How it compares to OWASP ZAP:

• Platforms: Web | License: Apache-2.0 | Primary tech: Groovy

7) JMeter

Apache JMeter is a mature performance and load testing tool for web, APIs, and protocols with a GUI and CLI mode.

• Strengths:

• How it compares to OWASP ZAP:

• Platforms: Web/API/Protocols | License: Apache-2.0 | Primary tech: Java

8) Karate

Karate is a DSL-based testing framework for APIs and web UIs (via Playwright/WebDriver) that unifies API testing, mocks, and data-driven flows.

• Strengths:

• How it compares to OWASP ZAP:

• Platforms: API/HTTP/Web | License: Apache-2.0 | Primary tech: DSL (Gherkin-like)

9) Lighthouse CI

Lighthouse CI automates Lighthouse audits (performance, accessibility, SEO, best practices) and enforces thresholds in pipelines.

• Strengths:

• How it compares to OWASP ZAP:

• Platforms: Web | License: Apache-2.0 | Primary tech: Node.js

10) PIT (Pitest)

PIT is a mutation testing system for the JVM that modifies bytecode to measure the effectiveness of your unit and integration tests.

• Strengths:

• How it compares to OWASP ZAP:

• Platforms: JVM | License: Apache-2.0 | Primary tech: Java

11) Paparazzi (Cash App)

Paparazzi is a screenshot testing library for Android that runs UI snapshot tests without requiring an emulator.

• Strengths:

• How it compares to OWASP ZAP:

• Platforms: Android | License: Apache-2.0 | Primary tech: Kotlin

12) Playwright

Playwright provides reliable browser automation across Chromium, Firefox, and WebKit with auto-waiting, tracing, and first-class parallelization.

• Strengths:

• How it compares to OWASP ZAP:

• Platforms: Web (Chromium/Firefox/WebKit) | License: Apache-2.0 | Primary tech: .NET, Java, Node.js, Python

13) Playwright Test

Playwright Test is the native test runner for Playwright with built-in reporters, traces, and parallel execution.

• Strengths:

• How it compares to OWASP ZAP:

• Platforms: Web | License: Apache-2.0 | Primary tech: JS/TS

14) Puppeteer

Puppeteer provides a high-level Node.js API to control Chrome/Chromium via the DevTools Protocol, enabling headless and headed automation.

• Strengths:

• How it compares to OWASP ZAP:

• Platforms: Chromium-based browsers | License: Apache-2.0 | Primary tech: Node.js

15) Rest Assured

Rest Assured is a fluent Java DSL for testing REST APIs, popular for backend validation and regression testing.

• Strengths:

• How it compares to OWASP ZAP:

• Platforms: API/HTTP (Java) | License: Apache-2.0 | Primary tech: Java

16) Robot Framework + SeleniumLibrary

Robot Framework is a keyword-driven test framework with a rich ecosystem; SeleniumLibrary enables browser automation within Robot tests.

• Strengths:

• How it compares to OWASP ZAP:

• Platforms: Web | License: Apache-2.0 | Primary tech: Python ecosystem

17) Selenide

Selenide is a concise, fluent wrapper over Selenium WebDriver for Java, emphasizing stable, readable UI tests with smart waits.

• Strengths:

• How it compares to OWASP ZAP:

• Platforms: Web | License: Apache-2.0 | Primary tech: Java

18) Selenium

Selenium is the de facto standard for web browser automation via the WebDriver protocol with language bindings across major ecosystems.

• Strengths:

• How it compares to OWASP ZAP:

• Platforms: Web (Browsers) | License: Apache-2.0 | Primary tech: WebDriver

19) Shot (Kakao)

Shot is an Android screenshot testing library that helps catch visual regressions across devices and configurations.

• Strengths:

• How it compares to OWASP ZAP:

• Platforms: Android | License: Apache-2.0 | Primary tech: Kotlin

20) Spock

Spock is a testing and specification framework for the JVM that blends BDD-style readability with powerful data-driven capabilities.

• Strengths:

• How it compares to OWASP ZAP:

• Platforms: JVM | License: Apache-2.0 | Primary tech: Groovy

21) Stryker

Stryker is a cross-ecosystem mutation testing framework (Node.js/.NET/Scala) that measures the strength of your tests by introducing code mutations.

• Strengths:

• How it compares to OWASP ZAP:

• Platforms: Node.js/.NET/Scala | License: Apache-2.0 | Primary tech: JS/TS/C#/Scala

22) Taiko

Taiko, from ThoughtWorks, is a Node.js browser automation tool with a readable API aimed at maintainable E2E tests on Chromium.

• Strengths:

• How it compares to OWASP ZAP:

• Platforms: Web (Chromium) | License: Apache-2.0 | Primary tech: Node.js

23) TestNG

TestNG is a flexible testing framework for the JVM supporting annotations, data providers, and powerful parallel execution.

• Strengths:

• How it compares to OWASP ZAP:

• Platforms: JVM | License: Apache-2.0 | Primary tech: Java

24) xUnit.net

xUnit.net is a modern unit testing framework for .NET that emphasizes extensibility, readability, and parallel test execution.

• Strengths:

• How it compares to OWASP ZAP:

• Platforms: .NET | License: Apache-2.0 | Primary tech: C#/.NET

Things to Consider Before Choosing a ZAP Alternative

• Scope and goals

• Language and ecosystem fit

• Ease of setup and learning curve

• Execution speed and stability

• CI/CD integration

• Debugging and traceability

• Community and maintenance

• Scalability

• Reporting and insights

• Cost

Conclusion

OWASP ZAP remains a popular, capable DAST tool for web and API security, especially for teams embedding automated security scans into CI/CD. Its strengths—open source licensing, extensibility, and CI friendliness—have made it a cornerstone for dynamic security testing.

That said, many teams are expanding beyond traditional DAST to cover broader quality concerns. If you’re focused on mobile, Appium, Espresso, and EarlGrey shine for functional automation. For browser E2E reliability, Playwright, Selenium, Selenide, Taiko, and Geb are strong contenders. For APIs, Rest Assured and Karate provide expressive validation. When performance and accessibility are priorities, JMeter and Lighthouse CI offer targeted capabilities. For test suite rigor, mutation testing with PIT and Stryker raises the bar. Screenshot testing tools like Paparazzi and Shot catch visual regressions early, while frameworks and runners like Robot Framework, Gauge, Spock, TestNG, and xUnit.net help you build maintainable, scalable pipelines.

Ultimately, the best choice depends on your goals. If you need runtime security scanning of web and APIs, ZAP is still a great fit. If your current pain points are functional stability, performance, accessibility, or test quality, the alternatives above may align better with your team’s workflows and technology stack. Many organizations combine these tools—using functional and performance testing to harden their applications and reserving ZAP (or another DAST) for targeted security gates—so they get comprehensive coverage without slowing down delivery.