I have a massive tool. In fact I have lots of them. That just sounds wrong. Anyway, I'm going to list ones I've found handy.
Local CSS Dev
- Edit and persist changes to your code using Devtools workspace
Image placeholders
So we want an image 250px by 250px for testing. There are some cool resources out there. Check out 8 of the top 10 placeholders if you don't like the ones below.
- Lorem pixel - generate pixel width and height images
- Placehold.it
Linting
Jshint was good for a while, but now we use eslint.
System design
Draw.io is an awesome system design tool.
Emmet
If you are doing any front end stuff you really need to know how to use emmet. Checkout this cool Emmet cheat sheet.
Server one-liners
These one liners are essential, runing a python server on one line plus many more.
Cross Browser Testing
Security
Mime types
A complete list of MIME types