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webKnossos is an open-source tool for annotating and exploring large 3D image datasets.
  • Fly through your data for fast skeletonization and proof-reading
  • Create 3D training data for automated segmentations efficiently
  • Scale data reconstruction projects with crowdsourcing workflows
  • Share datasets and annotations with collaborating scientists

Start using webKnossos - On your own server - User Documentation - Contact us


website and hosted version



Boergens, Berning, Bocklisch, Bräunlein, Drawitsch, Frohnhofen, Herold, Otto, Rzepka, Werkmeister, Werner, Wiese, Wissler and Helmstaedter webKnossos: efficient online 3D data annotation for connectomics. Nature Methods (2017) DOI:10.1038/NMETH.4331.

Read more about the original publication.


webKnossos is open-source, so you can install it on your own server.

Check out the documentation for a tutorial on how to install webKnossos on your own server.

For development installations, please see below.

Contributions, Contact and Support

We welcome community feedback and contributions! We are happy to have

For details on community contributions, please refer to our Contributing guide.

Contact us at

scalable minds offers commercial hosting, support and development services for webKnossos.

Development installation


This is only recommended for local testing. Docker 17+ and Docker Compose 1.18+ are required.

git clone -b master --depth=1
cd webknossos
docker-compose pull webknossos

Open your local webknossos instance on localhost:9000 and complete the onboarding steps in the browser. Now, you are ready to use your local webKnossos instance.

See the wiki for instructions on updating this development setup.

For non-localhost deployments, check out the installation guide in the documentation.



# webKnossos needs to be run from x86_64 environment (only applicable for arm64-based Macs)
arch -x86_64 /bin/zsh

# Install Homebrew package manager
/bin/bash -c "$(curl -fsSL"

# Install git, node.js, postgres, sbt, gfind, gsed
brew install openjdk@8 openssl git node postgresql sbt findutils coreutils gnu-sed redis yarn

# Set env variables for openjdk and openssl
# You probably want to add these lines manually to avoid conflicts in your zshrc
echo 'if [ $(arch) = "i386" ]; then' >> ~/.zshrc
echo '  export PATH="/usr/local/opt/openjdk@8/bin:$PATH"' >> ~/.zshrc
echo '  export PATH="/usr/local/opt/openssl/bin:$PATH"' >> ~/.zshrc
echo '  export LDFLAGS="-L/usr/local/opt/openssl/lib"' >> ~/.zshrc
echo '  export CPPFLAGS="-I/usr/local/opt/openssl/include"' >> ~/.zshrc
echo 'fi' >> ~/.zshrc

# Start postgres and redis
brew services start postgresql
brew services start redis

# Create PostgreSQL user
psql -c "CREATE DATABASE webknossos;"
psql -c "CREATE USER postgres WITH ENCRYPTED PASSWORD 'postgres';"
psql -c "ALTER USER postgres WITH SUPERUSER;"
psql -c "GRANT ALL PRIVILEGES ON DATABASE webknossos TO postgres;"

# Checkout the webKnossos git repository
git clone

Note: On arm64-based Macs (e.g. M1), you need to run webKnossos in an x86_64 environment (Rosetta 2). In case you accidentally started webKnossos in an arm64 environment, it is advisable to delete several caches ~/.m2, ~/ivy2, ~/.sbt, ~/.yarn-cache and run ./clean. Since Postgres and Redis are isolated processes, they can be run either from arm64 or x86_64 environments.

Ubuntu 20.04 LTS

sudo apt install -y curl ca-certificates wget
# Adding repositories for nodejs, sbt and yarn
curl -fsSL | sudo -E bash -
echo "deb all main" | sudo tee /etc/apt/sources.list.d/sbt.list
echo "deb /" | sudo tee /etc/apt/sources.list.d/sbt_old.list
curl -sL "" | sudo apt-key add
curl -sS | sudo apt-key add -
echo "deb stable main" | sudo tee /etc/apt/sources.list.d/yarn.list

sudo apt update
sudo apt install -y nodejs git postgresql postgresql-client scala sbt openjdk-8-jdk yarn redis-server build-essential libblosc1

# Assign a password to PostgreSQL user
sudo -u postgres psql -c "ALTER USER postgres WITH ENCRYPTED PASSWORD 'postgres';"
# Clone the git repo to the current directory
git clone -b master --depth=1

If you already have a different Java version installed, set the default version to Java 8:

  • run sudo update-alternatives --config java
  • when prompted, select the desired version

On older Ubuntu distributions: Please make sure to have the correct versions of node, PostgreSQL and java installed.

Manual Installation

  • Install Java JDK 8 (from Oracle or OpenJDK)
  • make sure JAVA_HOME and JDK_HOME are set and PATH contains path to JDK


node.js & yarn

Run locally

First, install all frontend dependencies via

yarn install

Note: During this installation step, it might happen that the module gl cannot be installed correctly. As this module is only used for testing webKnossos, you can safely ignore this error.

To start webKnossos, use

yarn start

This will fetch all Scala, Java and node dependencies and run the application on Port 9000. Make sure that the PostgreSQL and Redis services are running before you start the application.


For upgrades, please check the changelog & migration guide.


# Frontend linting
yarn run lint

# Format frontend code
yarn run pretty

# Format backend code
yarn pretty-backend

# Frontend type checking
yarn flow

# Frontend tests
yarn test-verbose

# End-to-end tests
docker-compose run e2e-tests


webKnossos was inspired by KNOSSOS.


  • Browser Stack for letting us test webKnossos on a variety of different devices Browserstack Logo
  • CircleCI for letting us run builds and tests on their CI