Validate HTML on local machine

You can download a vnu.jar release for checking HTML5 documents offline:

https://github.com/validator/validator/releases/download/latest/vnu.jar

Alternatively, you can install it using any of the following:

• docker run -it --rm -p 8888:8888 ghcr.io/validator/validator:latest
• npm install vnu-jar
• brew install vnu
• pip install html5validator

See https://validator.github.io/validator/ for more details.

many options:

see installation of w3c validation service:

http://validator.w3.org/docs/install.html

Firefox addons:

Firefox addon or other tool to locally validate HTML pages

https://addons.mozilla.org/en-US/firefox/addon/249/

Offline validator:

http://htmlhelp.com/tools/validator/offline/index.html.en