In the old days, I used to put my hand to FORTRAN, VMS, Pascal, VB, VBA, C, Postscript, though now I have to think a tad harder for that stuff, so only ask me if you are desperate (like, really desperate)!
Currently (2019) I work for three organisations:
In 2011, I was getting to know the excellent Silverstripe PHP CMS while working with the smart branding team at Brian R Richards. I have been very impressed by the ease of templating in Silverstripe, combined with bespoke database development, without being forbiddingly complicated. Earlier, I was using PHP Zend Framework (ZF) for Colenso and Westpac. A few years ago I installed OpenCart ecommerce projects and implementing Paypal to manage online purchases for an educational software company.
Prior to that, I was involved in two dollops of Paypal integration: for PharmaHealth I have created a Shopping Cart for online sales; and for Kenpo Karate I prepared the entry form for their 2010 Tournament at Eden Park Auckland, including Paypal payments for fees and extras. I find that Paypal is a bit of a challenge as there are huge numbers of options, and a deluge of documentation. However, it's the standard and familiar to customers around the world, which makes it commendable.