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 good first issue

  • 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 Angular 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:

Forking & cloning

You can clone the original repository with git clone but in order to contribute to the project via Pull Requests you probably want to fork the repository instead and then clone that fork to work on with

git clone<your GitHub username>/juice-shop.git

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

  • /frontend/package.json in the "version" property

  • /Dockerfile in the LABEL named org.opencontainers.image.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.

In case you want to open a PR before actually being finished with your work (e.g. because you’d like to see some intermediate CI/CD results) please tag the PR as Draft during its creation or later in its settings. This will natively prevent premature merges on GitHub from happening, while allowing your current work status to get reviewed already.

Contribution guidelines

The minimum requirements for code contributions are:

  1. The code must be compliant with the configured ESLint rules based on the JS Standard Code Style.

  2. All new and changed code should have a corresponding unit and/or integration test.

  3. New and changed challenges must have a corresponding e2e test.

  4. Linting, as well as all unit, integration and e2e tests should pass locally before opening a Pull Request.

  5. All Git commits within a PR must be signed off to indicate the contributor’s agreement with the Developer Certificate of Origin.


JavaScript Style Guide
npm run lint

The npm run lint script verifies code compliance with

  • the eslintrc.js rules derived from standard for all server-side JavaScript code

  • the frontend/eslintrc.js rules derived from standard-with-typescript for the frontend TypeScript code

  • the frontend/stylelintrc.js rules derived from stylelint-config-sass-guidelines for the frontend SCSS stylesheets

If PRs deviate from this coding style, they will break the CI/CD pipeline and will not be merged until refactored to match the coding rules.

In case your PR is failing from style guide issues try running npm run lint:fix over your code - this will fix many syntax issues automatically without breaking your code.


npm test                           # run all unit tests
npm run frisby                     # run all API integration tests
npm start & npm run cypress:open & # run all end-to-end tests

Pull Requests are verified to pass all 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 frontend/src/app/**/*.spec.ts

  • for the server-side routes and libraries in test/server/*Spec.ts

npm test

Integration tests

The integration tests in test/api/*Spec.ts 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 cypress/integration/e2e/*Spec.ts verifies if all client- and server-side vulnerabilities are exploitable. It passes only when all challenges are solvable on the score board.

npm start & npm run cypress:open &

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

If you have a web proxy configured via HTTP_PROXY environment variable, the end-to-end tests will honor this setting. This can be useful to e.g. run the tests through tools like OWASP ZAP or Burpsuite.

Manually testing packaged distributions

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.

npm install --production && 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.

Smoke tests

The shell script test/smoke/ performs some very basic checks on the availability of expected UI content and API endpoints. During CI/CD it is used to verify if the packaged distribution and Docker image start properly.

To manually use it on a packaged distribution run the following in your local repository clone root folder:

npm install --production && grunt package
cd dist && tar -zxf juice-shop-*.tgz && cd juice-shop_*
npm start &
../../test/smoke/ http://localhost:3000

Development mode for Angular frontend

Running npm install over and over for frontend code or view changes can be very time-consuming. Juice Shop can be run in a development mode provided through Angular CLI to avoid this. Run npm run serve from the root project folder and navigate to http://localhost:4200 instead of the usual port 3000. Whenever you change code in the frontend/src folder, the UI will recompile the affected bit and auto-reload the browser window for you.

Please note that the backend is still running on http://localhost:3000 in this mode and that changes in the backend code are not automatically applied.

Developing in a GitHub codespace

If you have access to GitHub Codespaces (which is in closed beta at the time of writing this), you can run an almost complete development environment for OWASP Juice Shop in the Cloud. It allows you to program and run the application entirely from your browser. The author has tested this to work very well even on a weak Chromebook.

  1. Go to

  2. Click New codespace and select juice-shop/juice-shop as Repository and develop as Branch. Then click Create codespace.

  3. Your codespace will be set up and launched. It automatically installs some plugins to make contributing easier our of the box:

    • Angular Language Service

    • ESLint

    • npm

    • stylelint

  4. After the container initializes, all application dependencies are automatically installed. This sometimes runs into some hang-up, so you might have to run npm install from the codespace terminal again if you see errors on npm start or ESLint complains about missing plugins.

  5. That’s it! You’re ready for developing on OWASP Juice Shop!

🚨 Please note that the client-side Unit tests and End-to-end tests will not work on GitHub Codespaces due to the lack of a Chrome installation in the underlying container.

Developer Certificate of Origin

The Developer Certificate of Origin (DCO) is a lightweight way for contributors to certify that they wrote or otherwise have the right to submit the code they are contributing to the project. Here is the full text of the DCO, reformatted for readability:

By making a contribution to this project, I certify that:

(a) The contribution was created in whole or in part by me and I have the right to submit it under the open source license indicated in the file; or

(b) The contribution is based upon previous work that, to the best of my knowledge, is covered under an appropriate open source license and I have the right under that license to submit that work with modifications, whether created in whole or in part by me, under the same open source license (unless I am permitted to submit under a different license), as indicated in the file; or

(c) The contribution was provided directly to me by some other person who certified (a), (b) or (c) and I have not modified it.

(d) I understand and agree that this project and the contribution are public and that a record of the contribution (including all personal information I submit with it, including my sign-off) is maintained indefinitely and may be redistributed consistent with this project or the open source license(s) involved.

Contributors sign-off that they adhere to these requirements by adding a Signed-off-by line to commit messages.

This is my commit message

Signed-off-by: Random J Developer <>

Git even has a -s command line option to append this automatically to your commit message:

$ git commit -s -m 'This is my commit message'


Continuous integration & deployment

The CI/CD and release pipelines for OWASP Juice Shop are set up as GitHub Action workflows:

CI/CD Pipeline

On every push to GitHub, a workflow consisting of several jobs is triggered on GitHub. Not only direct pushes to the master and develop branches are built, but Pull Requests from other branches or forks as well. This helps the project team to assess if a PR can be safely merged into the codebase. While unit and integration tests are executed on different combinations of Node.js and OS, the e2e tests are only run on the officially preferred Node.js version 20.x in order to avoid unnecessary feedback delays.

CI/CD Pipeline workflow on GitHub

Release Pipeline

For tag-builds (i.e. versions to be released) another workflow is triggered which packages the release_artifacts for Linux, MacOS and Windows for each supported Node.js version and attach these to the release page on GitHub and also published Docker images for the released version.

Release Pipeline workflow on GitHub

Handling of spam PRs

A small percentage of Pull Requests to are opened by GitHub users e.g. when "playing" with SCA / SAST tools or other automation tooling. Sometimes those users notice their mistake and close the PR right away, sometimes they don’t. Independent of who closed the PR (i.e. the original submitter or a Juice Shop core team member) it will be marked with the spam label.

Ban stages

Users who open a spam PR will be put on a 7-day ban for interaction with the organization. If a previously blocked user opens another spam PR, they will be blocked for 30 days, or even permanently after a third reoccurence.

These measures ensure that the core team can concentrate on the actual contributions to the project and not be kept busy by handling accidental or intentional spammers.

Instant permanent ban

Submitting obviously non-accidental spam PRs - especially during events like Hacktoberfest or Google Summer of Code - can lead to a permanent ban right away. The same applies for PRs with obviously malicious or abusive intent as detailed in the Juice Shop’s Code of Conduct.

Redemption from banishment

In the unlikely case that a user ended on the ban list by mistake or without comprehensible cause, they may contact and request to be removed from the ban list.