Im always trying to learn new things. Im passionate about learning new things, especially development. So much i started a small collaboration group of developers and slack group to collaborate new projects/ideas,get to know new people, and just to learn new things from each other. The group is not language specific developers only, but mostly consists of PHP/Laravel developers at the moment, so im always trying to grow that network as much as possible, so if you would like to join my network to collaborate new ideas or to just even talk to some cool cats, ill send you an invite any day. Anyways, back to my original reason for this post. Im mid level developer who considers himself pretty knowledgeable in PHP and Laravel. Im curious to what other developers use to learn new things. Im constantly questioning my skillset and compare myself to senior developers who always blow me away with their knowledge which often makes me feel like i dont know enough. Currently I use resources such as:

-laracasts.com
-serversforhackers.com
-digital ocean articles or any textbook that wont cost me an arm and a leg lol

I mean i just want to learn about tech related stuff always but currently interested in learning specifically about development topics such as:

- Server administration because i would consider this my weakest skill set (things like provisioning,nginx/security, deployment)
- Continous Integration (as ive never been at a job that practices it)
- RESTful APIs(as ive never developed one)

and so much more but i wont waste your time with my never ending list. What resources/tools do you guys use for your learning?