Which Enterprise Products started out solving SMB problems?

I feel like many great solutions for small businesses started out as founders solving their own small biz problems, but found a more lucrative market in the enterprise, leaving the same problem in the SMB space unsolved or unaffordable?

I feel like there is either a lot of opportunity left for picking...or there is an apparent problem without the economics to support SMBs and founders can avoid headaches knowing which problems were solved, but only found a viable market in the enterprise.