First and foremost is always going to be HUB, you'll find that abbreviation in a lot of Hansa studies; for Hansisches Urkundenbuch - Eleven volumes of editions of Hanseatic documents - available here

Then there's a dozen or more volumes of Hansische Geschichtsquellen, those too (and tons more) are all online at Hansischer Geschichtsverein

Just the above are easily a dozen bookshelves worth (literally), but some random other sources:

Hamburgisches Urkundenbuch - link to the first of multiple volumes.

Lübeckisches Urkundenbuch

Bruns, Die lübeckischen pfundzollbücher von 1492-1496 (pound toll books are useful where available)

Jenks, Das Danziger Pfundzollbuch von 1409 und 1411

Stadtbuch der Jungstadt Danzig, 1400-1459

Diplomatarium Suecanum - has some Hanseatic documents in there too.