Photo editors & resizer
Color names
PX to EM convertor v.v.
PNG vs JPG
SCSS to CSS conv.
Google Hosted Libraries
HTML beautifier
CSS beautifier
Javascript beautifier
HTML minifier
CSS minifier
Javascript minifier
HTML Cheat Sheet
CSS Cheat Sheet
Javascript Cheat Sheet
HTML generators
CSS generators
Javascript compressor
W3C HTML Validator
W3C CSS Validator
W3C Link Validator
HTML Formatter
Powermapper.com
Unminify.com
Simple image resizer
Compressor.io
Alt codes, HTML codes