Skip to content

Open source system for contact tracing at universities, based on scanning QR-codes. Written in Kotlin.


Notifications You must be signed in to change notification settings


Repository files navigation

Campus QR

Due to the current situation around the COVID-19 pandemic, Studo developed an open source system for contact tracing at universities. When entering a lecture hall or seminar room, students and teachers can scan a QR code attached to the door or in the entrance area. Campus QR allows creation and management of those QR codes. An optimal implementation in terms of data protection and security are goals of this project.

Campus QR can additionally be used as access management system: Access to locations like department buildings is only granted by explicit invite. Users scan the QR code attached to the entrance. If access is granted, a unique animation with access information is shown at the users mobile device to allow entrance by a doorman or web-hook based door unlocking systems. Access control or successful check-ins can also be verified by an employee during a lecture in bulk, so lecturers can validate within seconds if hundreds of students have successfully checked in.

The system is open source and can be hosted by the university itself. The web app is available as stand-alone application. The Studo app integrates the provided Android and iOS reference implementation to allow offline dispatching of check-in events.


In 2021, Campus QR received the IÖB-awarded seal from the Public Procurement Promoting Innovation Austria (IÖB).


  • Simple: Both check-in and administration have a clean and easy to use user interface.
  • Secure: State-of-the-art security measurements, permission-based user management with only hashed password saving and encryption.
  • Accessible: Mobile optimized and responsive check in and management UI on all major devices and browsers without installation.
  • Open source: 100% of the code is open source and is without further modification production ready.
  • Self-hostable: The whole application can be hosted by the university itself. Studo provides support in hosting the application.
  • Managed hosting: Secure and GDPR-compliant hosting in the EU with encrypted-at-rest databases by Studo to go into production within days.
  • Multiple languages: All elements of the app are localized to English and German to be inclusive of all students, employees and guests of a university.
  • Fully configurable: Names, logos, links, privacy policy and text content is configurable in production without changing the source code.
  • Exportable: Check-ins at specific locations and check-ins from specific people can be downloaded as csv file to open them in Excel.
  • Infection tracing: Fast and reliable tracing of infection chains.
  • Automatic data deletion: After a configurable time (default: 4 weeks) the check-in data will be automatically deleted to comply with the GDPR.
  • Multipermission administration: The moderation frontend of Campus QR can be used by thousands of employees of a university.
  • Access management: Creation of specific access for students or guests within selected time frame to allow a controlled reopening of university buildings.
  • Visitor list export: Simple doorman specific interface with upcoming access permits
  • Scalable access verification: Access control can be verified by a doorman or lecturer in parallel to avoid crowds around entries. A unique access verification code is generated daily for easy parallel verification.
  • External identity management: SSO, LDAP (using JNDI) and OAuth2 are supported by Ktor authentication packages and fully configurable LDAP integration.
  • Logging: Optional User-Agent and IP address logging for auditing. (Disabled by default - privacy by default)
  • API access: A shared key can be optionally defined to grant admin access to external services: Add the X-Authorization: [authSharedSecret] header to the request to authenticate as administrator (sharedSecretUser).
  • E-Mail restriction: Definition which e-mail addresses can be entered on check-in to force university email addresses.
  • Manual check out: Users can check out by scanning the check-in QR code again or scanning a generic check-out QR code.
  • Automatic check out: In case users forget to check-out, they get automatically checked-out after a configurable amount of minutes have passed.
  • Multi check in: Locations can contain sublocations: Users can check-in in whole buildings and then further check-in in rooms inside the building.
  • Seat support: A QR code can be generated for whole locations (like rooms or buildings) or per seat (e.g. one QR code per lecture hall seat).
  • Seat filtering: With enabled seat support, potentially affected people can be filtered by their seats. This allows differentiating between two types of contacts:
    • "K1 contact": People who were in direct contact with an infected person.
    • "K2 contact": People who where only in the same location and time but sat far away to the infected person.

Managed hosting features

Campus QR can be hosted by the university itself or by Studo. When hosted by Studo, the following hosting features are available per default:

  • Horizontal application scaling: By running several API nodes in parallel, the application infrastructure can be scaled to as many nodes as required.
  • Zero-downtime operations: Deployment, container restarts and upgrades are zero-downtime operations: New containers have to be available first, before stopping the old containers.
  • Automatic security updates: Containers apply OS and JVM security updates with zero downtime.
  • Real time metrics and logs: Application nodes and database nodes allow easy monitoring and auditing.
  • Scalable database infrastructure: The MongoDB database runs in high availability mode (replicaset) with 2 active data nodes, 1 backup node and 1 arbiter to ensure zero downtime (99.96% uptime guaranteed by SLA).
  • Dockerized database containers: Database servers are dedicated processes sealed in docker containers. It allows seamless database upgrades with zero downtime if more space or memory is required.
  • Database backups: Daily automated encrypted backups with retention policies to auto-delete old backups.
  • Database security: SSL connections and Encryption-at-Rest are enabled per default.
  • Optimal database performance: SSD-like performance on SAN-backed dedicated MongoDB processes.
  • Dedicated expect care and support: Your application will be manged by an expert team that handles an infrastructure with more than 10.000 requests per minute.
  • GDPR compliant: Hosted in the EU on ISO/IEC 27001:2013 certified datacenter infrastructure.


User Frontend

Students and all visitors scan a printed QR code and check in with their e-mail address.

checkin printout

Moderation Frontend

Employees of a university can login, create locations, report infections to notify affected people and manage users. login locations tracing userManagement accessControl

Self hosting


The following environment variables need to be configured:

  • PORT (default: 8070): Port where the web application will listen to
  • HOST (default: By default the web application is accessible from every host. Set it to if the web application should only be accessible from localhost.
  • MONGO_URI (default: mongodb://localhost:27017/campus-qr): Database URI to store further configuration, locations, check-ins and moderation users. Make sure that the database is either not accessible from another host or provide authentication parameters in the URI.

Development compilation

Start the backend application by the IntelliJ run configuration Server or alternatively with ./gradlew server:run. After having the backend running, start the moderator frontend application by the IntelliJ run configuration Debug Web-Frontend or alternatively with ./gradlew browserDevelopmentRun -t. You can now access the moderator frontend with the proxied local backend via https://localhost:8072. When debugging with the Debug Web-Frontend run configuration, you can also set breakpoints in IntelliJ while testing the web-frontend in the newly opened Chrome window (first compilation might take a while). Hot reloading of the moderator web frontend is also enabled.

Production compilation

Build the whole application with ./gradlew stage to run it with java -jar Server.jar. This also compiles the moderator frontend and bundles it into the jar.

First time setup

The default admin email address is with password admin. Please change it immediately after your first login to the moderation frontend.

Change at least the following values in the configurations collection in the connected MongoDB. Note that this collection will be automatically created after the first launch of the application:

  • userTosUrl_en / userTosUrl_de: Links at the check-in view.
  • imprintUrl_en / imprintUrl_de: Links at the check-in view.
  • baseUrl: Needed for CORS protection and logout redirect URL.
  • qrCodeBaseUrl: URL prefix for generating QR codes. White-labeling, LDAP configuration, privacy settings and further configuration parameters can also be tweaked by changing the appropriate stringValue and intValue in the configurations collection.


When self-hosting Campus QR, create a setup that ensures at least weekly updates of the upstream source code to quickly react on updates.

Deployment on generic PaaS with Procfile

This repository provides a generic Procfile for easy deployment to most PaaS providers like Scalingo.

Calling the stage gradle task (./gradlew stage) will build a fat jar in Server.jar. This jar file already contains the moderation frontend. If your PaaS provider calls a different build task, inject the stage task as dependency there.

The server assumes that the PaaS provider provides all necessary environment variables mentioned in the Setup section.

Deployment on self-hosted hardware with Docker

Download the Dockerfile and docker-compose.yml.
Adjust the provided docker-compose.yml, change all default values and define all necessary environment variables mentioned in the Setup section.
Start server via docker-compose up -d --build and use MongoDB Compass, mongo-express or another tool to change the params mentioned in First time setup section.

To run in production, running a reverse-proxy/loadbalancer/gateway with https-termination is required.

Project structure

This Git repository is a Kotlin Multiplatform Project using Gradle. Opening the project in IntelliJ works out of the box.


For the backend the project uses Kotlin for Server-side Development by running on the JVM. Supported JVM versions are JVM 11 LTS and the latest JVM version. This backend code is located in the subfolder server/src/main and uses shared code from common/src/commonMain.

User Frontend

The user frontend allows checking in with a QR code. This module is HTML5 based, the mobile optimized HTML5 is generated by the server. The user frontend communicates via HTTPS request with the server.

Moderation Frontend

The moderation frontend allows creation of new QR codes, QR code management and user notifications. This module is a React project using Kotlin/JS to generate the JavaScript code that runs in a web browser. The moderation frontend communicates via HTTPS API calls with the server. The moderation frontend code is located in the subfolder moderatorFrontend/src/jsMain and uses shared code from common/src/commonMain.

Android reference implementation

The native Android reference implementation to scan QR codes is provided in the subfolder campus-qr-android and might be used by Android applications to allow scanning the QR codes while being offline and dispatching the check-in event when being online again.

iOS reference implementation

The native iOS reference implementation to scan QR codes is provided in the subfolder campus-qr-ios and might be used by iOS applications to allow scanning the QR codes while being offline and dispatching the check-in event when being online again.

Code Style Guide

The project follows the official Kotlin Coding Conventions with two additions: Line wrap is 140 characters, and indentation is 2 instead of 4 spaces (continuation indent is 4 instead of 8 spaces) on all file types. Please follow these conventions when creating a pull request. Pull requests are welcome!


Open source system for contact tracing at universities, based on scanning QR-codes. Written in Kotlin.