# Validation

Whisk offers live HTML5, CSS, XHTML5, and SVG validation.

Under-the-hood, this is same engine as the W3C validator: The Nu Html Checker (v.Nu) (opens new window).

Live validation is enabled by checking the Live validation box in the Validation Inspector. You can also validate in non-live manner by click Validate page or choosing Text > Validate Page (Command-K). Issues are shown in the Validation Inspector table view and yellow or red underlines will appear in the Source Editor when the validation has encountered a mistake.

A document with some issues.
A document with some issues.

Error descriptions are reported in the table, and clicking on them will select the offending line of text. The table can be temporarily cleared via the Text > Clear Validation menu item.

The first validation needs to start the validation process, so may take about 5 seconds before results are shown. Progress is displayed at the bottom of the Validation Inspector.

You can quickly move between errors via the Text > Next Error and Text > Previous Error menu items, or Control-Up/Down.