Total Software Development System v1.6 (TSDS) by Piratebusters Software is a collection of tools for the Commodore 64 and 128 used for developing software.  Here is a quick blurb from a review by Chris Zamara that I found in TPUG News Volume 1, Number 2:

At first glance, TSDS appears to be just a colletion of standard utilities: an editor enhancement utility a la BASIC aid, an assembler, a sprite editor, a character editor, and a sound effects generator - the kind of thing to make a jaded programmer yawn. After using the package for a short while, however, it becomes obvious that the programs in TSDS are the product of a programmer who has created high quality tools for his own use, and honed those tools to a keen edge.

You can find the full review here - http://www.tpug.ca/tpug-media/nl/v1n2.pdf