My favorite online PHP sandbox answer demo

codepad-viper7.com is forever gone.

I now have found a decent sandbox site that works just like codepad-viper.

https://tehplayground.com

You'll always see me at php

Bookmarks on SO that you might think is useful:

Second Rikudo's deprecation note on MySQL API:
http://stackoverflow.com/a/12860140/3859027

Handle libxml errors:
http://stackoverflow.com/a/17559716/3859027

Remove query strings:
http://stackoverflow.com/a/1251650/3859027

MultipleIterator Usage:
http://stackoverflow.com/a/25218722/3859027

Asynchronous shell execution:
http://stackoverflow.com/a/222445/3859027

Human triggered click:
http://stackoverflow.com/a/6692173/3859027

DOMDocument save output with html wrapper:
http://stackoverflow.com/a/4879970/3859027
http://stackoverflow.com/a/22490902/3859027

DOMDocument utf8 workaround:
http://stackoverflow.com/a/8218649/3859027

DOMDocument Regressive child replacement:
http://php.net/manual/en/domnode.replacechild.php#50500

Get website screenshot thumbnail thru URL:
http://api.thumbalizr.com/?url=http://www.google.com.au&width=200

XPath Injection:
http://stackoverflow.com/a/194071/3859027

Create dot separated config:
http://stackoverflow.com/a/8545741/3859027

Get dot separated config:
http://stackoverflow.com/a/24573763/3859027

Open simulator through terminal:
https://stackoverflow.com/a/17118386/3859027

Fallback option for CSS aspect-ratio:
https://stackoverflow.com/a/63237098/3859027