- 1980 - Zmacs, first editor to blink matching paren at cursor
- 2001 - Paren Face, dim parens
- 2004 - S-expression boxes, color scope concept
- 2004 - mwe-color-box.el, color scopes and hide parens
- 2005 - Scratch, not actually sure if close to lisp
- 2010 - Rainbow delimiters, color-code parens
- 2010 - Scheme bricks
- 2012 - Lisping, iPad lisp editor w/ boxes
- 2013 - indent-guide.el
- 2014 - Rainbow blocks, color-code blocks
- 2014 - closure-bricks.el
- 2015 - Frame-based editing, not lisp
- 2015 - Plastic
- 2016 - Cirru, horizontal and vertical lines replace parens
- 2017 - Fructure
- https://www.deepdyve.com/search?query=frame-based+editing
- see who cited Scratch: http://dl.acm.org/citation.cfm?id=1868358.1868363
- check comments for related tools: https://news.ycombinator.com/item?id=14609215
- http://lemonodor.com/archives/001207.html