Ask HN: Building multiple SaaS apps or combine them as a big collection?

I'm building tools to help me build saas apps. I have about four right now with about 12 more ideas I want to make. Most are small (link shortener, analytics, basic CRM, etc) so I was thinking of making a site that includes all of these tools for a single monthly fee vs charging for each one. The other approach would be to make each of these tools their own app (domain, design, etc) and connect them with the same authentication so if you're logged in one you can access the others. Thoughts on either of these approaches?