Concordion

Concordion is an open-source specification-by-example tool for teams that want readable examples to serve as automated checks and shared documentation. It is most compelling for Java teams already working with JUnit and build tooling. Its generated reports connect test outcomes to the examples, but Jenkins publishing requires attention to a security-policy workaround.

Overview

Concordion instruments examples in a specification and runs them against the system under test. Each run produces documentation that marks passing and failing assertions and, on failure, shows expected and actual values. Tables and links to related specifications can make those results useful to stakeholders as well as developers and testers. The approach is valuable when a team keeps its examples aligned with the software; otherwise, generated documentation cannot stay a dependable account of behavior.

Fixtures can call application code directly or drive deployed interfaces through libraries such as Selenium WebDriver, JAX/WS, JAX/RS, or JDBC. Java fixtures use JUnit, and Concordion.NET integrates with NUnit. The project dates to 2006 and is maintained by volunteers, with a Google Group and GitHub for contact and participation.

Key features

Specifications and development workflow

The Java distribution offers HTML and Markdown specifications, with Java dependencies available through Gradle and Maven; a full ZIP includes source code and dependencies. C# options are also offered. IntelliJ IDEA support includes completion, navigation, and test running, and handles both HTML and Markdown. The Eclipse plugin supports HTML specifications but not Markdown, so teams choosing that editor should account for the narrower format support. Java users running concordion:run with a JUnit 4 fixture also need JUnit Vintage.

The integration choices span command-line execution, Gradle, Maven, IntelliJ IDEA, Eclipse, Spring, and Jenkins. That breadth makes Concordion adaptable to several Java workflows, though it does not remove the work of fitting executable specifications into an existing build and test process.

Extensions and reports

Extensions can add commands and event listeners or change generated documentation. Examples include Excel specifications, parallel runs, screenshots, and logging tools. Jenkins' HTML Publisher plugin can publish reports, retain per-build history, and provide output as a ZIP file. However, Concordion reports use inline CSS and JavaScript, which Jenkins Content Security Policy defaults can block. Teams can relax that policy as a workaround, but organizations that cannot do so should treat Jenkins publishing as a significant deployment constraint.

Pricing

Concordion is free and open source under the Apache License 2.0. The Open source plan costs nothing and provides the Java library. There is no free trial because the software is already free. This suits teams able to integrate and maintain a library themselves; volunteer maintenance and community contact through Google Group and GitHub are a less formal support model than a paid vendor relationship.

Platforms

Concordion supports Linux, macOS, Windows, and self-hosted use. Execution is local. It supports Gherkin, parallel execution, browser testing, and API access, making it relevant beyond specifications that only check code in-process.

Who it's for

Concordion is aimed at stakeholders, analysts, developers, and testers who want examples of expected behavior to double as checks and documentation. It is a particularly natural choice for Java teams using JUnit with Maven or Gradle, or teams that need to exercise deployed interfaces through libraries such as Selenium WebDriver. Teams that want vendor-backed support, cannot maintain specifications alongside code, or need Jenkins reports to work under an unchanged restrictive policy should look elsewhere.

Pros and cons

• Pros: Executable examples produce readable documentation with explicit pass/fail outcomes and expected-versus-actual values, helping technical and nontechnical readers review the same behavior.
• Pros: Java, C#, multiple specification formats, IDE plugins, build tools, and extensions give teams options for integrating specifications into development and reporting workflows.
• Cons: Eclipse support excludes Markdown, unlike the IntelliJ plugin, which supports both HTML and Markdown.
• Cons: Jenkins' default Content Security Policy can interfere with report styling and scripts, and the workaround involves relaxing that policy.
• Cons: Volunteer maintenance means support is centered on community channels rather than a commercial support arrangement.

Alternatives

Consider Serenity BDD for another free open-source option that spans Android, iOS, Linux, macOS, self-hosted, web, and Windows; its JUnit 4 support is deprecated and planned for removal in Serenity 6.0.0. FitNesse is another free open-source project, with no commercial plans or limits stated, for readers comparing free options across API, desktop, self-hosted, and web platforms.

Cucumber Open may fit readers seeking a free open-source option across Android, API, Linux, macOS, and Windows; Cucumber Reports are free. Ginkgo is a free Go testing framework for Linux, macOS, or Windows, with v2 as its current supported major version.

CukeTest offers a free Lite plan with visual feature editing and JavaScript and Python, but some built-in automation libraries have usage limits and the plan caps automation API calls at 500. Karate is a free MIT-licensed framework for REST, GraphQL, and SOAP API testing, browser and desktop UI automation, and Gatling performance testing.

Reqnroll has a free Community plan with framework use, Visual Studio and Rider integration, community plugins, and community support; its Professional plan is 40010.00 EUR per. LightBDD is a free, BSD 2-Clause licensed option for Linux, macOS, or Windows, with no paid tiers stated.

Browse more options in BDD Testing Tools.

Verdict

Concordion is a strong fit for teams—especially Java teams—that want specifications to function as executable checks and documentation in the same workflow. Its reports make failures legible, and its build, IDE, and extension options give teams room to adapt it. Choose another tool if volunteer-led support is insufficient or Jenkins policy cannot accommodate the report workaround.