Saleslogix (SLGX) was a Salesforce competitor which went public during my tenure but ran out of cash in 2001.  I worked on SLGX my first year and then became team lead and architect for SupportLogix.

We purchased a small call center company to merge into SLGX as a companion offering.  The codebases  were vastly different, however.  SLGX was quite sophisticated.  It's a CRM platform with a SQL engine supporting several RDBMs, a form designer and a VBA-ish scripting language.  The call center app was kindergarten-level code with a normalized database versus SLGX's denormalized one.

It was a nightmare project.  But we delivered it in nine months and ten months later it paid for itself.  It's a success that I rarely think about. SLGX is the most sophisticated software I've ever done, written in Object Pascal (Delphi) with extremely high customization. Our customers were small IT companies who customized and resold SLGX to their customers.

It was my first commercial software and I'm surprising it's still in use.  It was written for a pre-phone world and did database synchronization over a modem.