The LinkValidator is a tool for checking link in user input. It is part of the system extension linkvalidator.

If you are using Composer, you can install it like any other (Core) extension requiring the package typo3/cms-linkvalidator:

composer require typo3/cms-linkvalidator

If you are using Composer and not working with the latest version of TYPO3 you will need to add a version constraint:

composer require typo3/cms-linkvalidator:"^10.4"

If you want to use the LinkValidator in the Scheduler, the system extension scheduler also needs to be installed:

composer require typo3/cms-scheduler

If you are not using Composer, you may have to activate the LinkValidator in the Extension Manager.

Activate the LinkValidator in the Extension Manager

Activate the LinkValidator in the Extension Manager

LinkValidator uses the HTTP request library shipped with TYPO3. Please have a look in the Global Configuration, particularly at the HTTP settings.

There, you may define a default timeout. Generally, it is recommended to always specify timeouts when working with the LinkValidator.