On the search results page, the diet pulldown filter allows you to restrict by a number of dietary options including vegan, vegetarian, pescatarian, gluten-free, keto, low carb, high protein and more.
In addition to this, specific ingredients or entire groups can be excluded by prefixing with "-". Ingredient groups that can be exclude include nuts, soy, cheese, alliums (onion family) and fodmaps.
For example:
cookie nut -walnut -almond (any nuts apart from almonds and walnuts)
What's more, if you go to ckbk's nutrition settings page, you can set your preferences so that searches on ckbk are optimised to your dietary needs by default:
