Org Installable Apps

Roll-Up Helper

https://appexchange.salesforce.com/appxListingDetail?listingId=a0N30000009i3UpEAI

 

Mass Action Scheduler 

Create scheduled actions, declaratively and without code.

https://douglascayers-org.github.io/sfdx-mass-action-scheduler/

 

Declarative Lookup Rollup Summaries (DLRS)

https://github.com/afawcett/declarative-lookup-rollup-summaries