Ask HN: Developer-Focused CRM with a Solid API?

I want to integrate a CRM into a SaaS I'm building - https://kvdb.io - but many of the existing solutions are either too complex or don't provide a nice enough API. I'm looking to enable and record events from this kind of workflow:

1. User signs up on my site

2. User performs an action

3. Transactional email is sent

4. User clicks a link in the email

5. User performs actions in product

etc.

I'd like to see all of this activity in my admin piece, in a kind of timeline fashion to enable measuring product engagement and identifying issues (feature use, abandonment, etc.). I'm not sure if there are third-party services that enable this kind of tracking, but I'd love to pull all this data into my admin site rather than going to another site to view it, so I can enrich the CRM data with my own. I think I'd be reasonably happy with an API-only CRM!

How's everyone else doing customer management and event tracking for their SaaS apps?