https://news.ycombinator.com/jobs is probably a good enough sample to answer that question. The answer seems to be Greenhouse and Lever.
(Some companies link to job descriptions on their own site and/or embed the ATS-hosted form in their site, but many of those use Greenhouse or Lever too. The companies linking directly to ATSes do seem representative.)
(Some companies link to job descriptions on their own site and/or embed the ATS-hosted form in their site, but many of those use Greenhouse or Lever too. The companies linking directly to ATSes do seem representative.)