https://www.group-office.com https://www.group-office.com Basic version is open source but the premium is only 200$ a year if you self host it. They have out o

https://www.group-office.com https://www.group-office.com Basic version is open source but the premium is only 200$ a year if you self host it. They have out of the box Debian packages so it's easy to run. It's the most feature packed crm we have found and we have used it for clients the last 8 years.