Ask HN: During startup phase, what lead managment software you use?

During startup phase, how do you manage all your contacts?

During initial phase when as a founder you are doing everything including sales as well, what tool is best for managing all your leads.

There are many sales lead management softwares but I am not sure whether they are a good fit for an entrepreneur (who is primarily not a sales person). HINT: They might be too complicated. Another HINT: I have never used them so I might be wrong.

Do you use any tool which is an obvious choice currently?