There are a ton of tech companies in Pioneer Square. Geekwire has this 5 year out of date map, https://www.geekwire.com/2013/pioneer-square-tech-map-techie... but just walking through there, Pioneer Square is tech city during the day. From trendy bars to expensive boutique clothing stores. Other startups, such as Real Self, have come into being since that (ancient) list was made.

There are multiple co-working spaces within blocks of each other, The Pioneer Collective, Galvanize, Impact Hub, and at least 2 accelerators that I know of are based near Pioneer Square.