Contribute to development

If you would like to contribute to OWASP Juice Shop but need some idea what task to address, the best place to look is in the GitHub issue lists at

"help wanted" label on GitHub "good first issue" label on GitHub

  • Issues labelled with help wanted indicate tasks where the project team would very much appreciate help from the community
  • Issues labelled with good first issue indicate tasks that are isolated and not too hard to implement, so they are well-suited for new contributors

The following sections describe in detail the most important rules and processes when contributing to the OWASP Juice Shop project.

Tips for newcomers

If you are new to application development - particularly with AngularJS and Express.js - it is recommended to read the Codebase 101 to get an overview what belongs where. It will lower the entry barrier for you significantly.

Version control

The project uses git as its version control system and GitHub as the central server and collaboration platform. OWASP Juice Shop resides in the following repository:

Branching model

OWASP Juice Shop is maintained in a simplified Gitflow fashion, where all active development happens on the develop branch while master is used to deploy stable versions to the Heroku demo instance and later create tagged releases from.

Feature branches are only used for long-term tasks that could jeopardize regular releases from develop in the meantime. Likewise prototypes and experiments must be developed on an individual branch or a distinct fork of the entire project.


Any release from master is tagged with a unique version in the format vMAJOR.MINOR.PATCH, for example v1.3.0 or v4.1.2.

Given a version number MAJOR.MINOR.PATCH, increment the:

  1. MAJOR version when you make incompatible API changes,
  2. MINOR version when you add functionality in a backwards-compatible manner, and
  3. PATCH version when you make backwards-compatible bug fixes.1

The current version of the project (omitting the leading v) must be manually maintained in the following three places:

  • /package.json in the "version" property
  • /app/package.json in the "version" property
  • /Dockerfile in the LABEL named org.label-schema.version

All other occurrences of the version (i.e. packaged releases & the menu bar of the application itself) are resolved through the "version" property of /package.json automatically.

Pull requests

Using Git-Flow means that PRs have the highest chance of getting accepted and merged when you open them on the develop branch of your fork. That allows for some post-merge changes by the team without directly compromising the master branch, which is supposed to hold always be in a release-ready state.

It is usually not a big deal if you accidentally open a PR for the master branch. GitHub added the possibility to change the target branch for a PR afterwards some time ago.

Contribution guidelines

The minimum requirements for code contributions are:

  1. The code must be compliant with the JS Standard Code Style rules
  2. All new and changed code should have a corresponding unit and/or integration test
  3. New and changed challenges should have a corresponding e2e test
  4. All unit, integration and e2e tests must pass locally

JavaScript standard style guide

As a preliminary step, the npm test script verifies code compliance with the standard style before running any test. If PRs deviate from this coding style, they will immediately fail their build and will not be merged until compliant.

JavaScript Style Guide

In case your PR is failing from style guide issues try running standard --fix over your code - this will fix all syntax or code style issues automatically without breaking your code.

:point_up: For this you will need to install standard globally on your computer with npm i -g standard.


npm test           # check for code style violations and run all unit tests
npm run frisby     # run all API integration tests
npm run protractor # run all end-to-end tests

Pull Requests are verified to pass all of the following test stages during the continuous integration build. It is recommended that you run these tests on your local computer to verify they pass before submitting a PR. New features should be accompanied by an appropriate number of corresponding tests to verify they behave as intended.

Unit tests

There is a full suite containing isolated unit tests

  • for all client-side code in test/client
  • for the server-side routes and libraries in test/server
npm test

Integration tests

The integration tests in test/api verify if the backend for all normal use cases of the application works. All server-side vulnerabilities are also tested.

npm run frisby

These tests automatically start a server and run the tests against it. A working internet connection is recommended.

End-to-end tests

The e2e test suite in test/e2e verifies if all client- and server-side vulnerabilities are exploitable. It passes only when all challenges are solvable on the score board.

npm run protractor

The end-to-end tests require a locally installed Google Chrome browser and internet access to be able to pass.

Mutation tests

The mutation tests ensure the quality of the unit test suite by making small changes to the code that should cause one or more tests to fail. If none does this "mutated line" is not properly covered by meaningful assertions and the mutation testing engine that will inform you about this.

npm run stryker

Currently only the client-side unit tests are covered by mutation tests. The integration and end-to-end tests are not suitable for mutation testing because they run against a real server instance with dependencies to the database and an internet connection. The mutation tests are intentionally not executed on Travis-CI due to their significant execution time.

Continuous integration & deployment


The main build and CI server for OWASP Juice Shop is set up on Travis-CI:

On every push to any branch on GitHub, a build is triggered on Travis-CI. A build consists of several jobs: One for each version of Node.js that is officially supported by the application. Each job performs the following actions:

  1. Clone the repository and checkout the branch to build
  2. Build the application
  3. Execute the quality checks consisting of
    • Compliance check against the JS Standard Code Style rules
    • Unit tests for the Angular client
    • Unit tests for the Express routes and server-side libraries
    • Integration tests for the server-side API
    • End-to-end tests verifying that all challenges can be solved
  4. Upload of the quality metrics to Code Climate
  5. Deployment to a Heroku instance
  6. Trigger some monitoring endpoints about the build result

Pull Requests are built in the same manner (steps 1-3) to assess if they can safely be merged into the codebase. For tag-builds (i.e. versions to be released) an additional step is to package release-artifacts for Linux for each Node.js version and attach these to the release page on GitHub.


AppVeyor is used as a secondary CI server to check if the application can be built on Windows. It also packages and attaches release-artifacts for Windows in case a tag-build is executed:

Testing packaged distrubutions

During releases the application will be packaged into .zip/.tgz archives for another easy setup method. When you contribute a change that impacts what the application needs to include, make sure you test this manually on your system.

grunt package

Then take the created archive from /dist and follow the steps described above in Packaged Distributions to make sure nothing is broken or missing.


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