The majority of the employers on CoolWorks are small to medium businesses who do not participate in the H-2B Visa program, and are therefore unable to assist with H-2B Visa Extension requests.
Employers do have the option to select a checkbox when they post an ad to indicate if they are able to accept applications from J1 or H-2B Visa holders. Those employers can be found on this page: https://www.coolworks.com/international-job-seekers
Sometimes employers will also indicate in the text of their individual job postings that they are able to accept applications from H-2B visa holders. One way to locate them is by doing a keyword Search for "H-2B." However, be advised that this search query will also return results with messaging that includes "We are not able to hire H-2B Visa holders." For this reason, it is not advised that Visa recipients submit job applications to an employer unless you find them on the International Job Seekers page, or they explicitly state in their advertising materials that they are able to accept applications from H-2B Visa holders.