Open SaaS is still very new, but there are a couple that used the "old" version of it, which basically gave us an idea for Open SaaS. For example:

- CoverLetterGPT (https://coverlettergpt.xyz/) - generate a cover letter based on your CV and job description

- Etsy description generator (this one even got acquired): https://dev.to/wasp/from-idea-to-exit-building-and-selling-a...