• Using the .jar
• Using pip install
• Using pre-compiled binary

This last option makes it easy to setup a HTML linter in Gitlab CI pipelines:

lint-html:
  stage: test
  script:
  - apt update -y && apt install -y curl unzip
  - ...  # generate HTML content in public/
  - curl -ROLs https://github.com/validator/validator/releases/download/latest/vnu.linux.zip
  - unzip vnu.linux.zip
  - vnu-runtime-image/bin/vnu --skip-non-html public/