I am among the top 3 Prestashop developer in Freelancer.com.
Prestashop ----- Shipping modules ---- Api's used -- , DPD shipping api , Pakkelabels, Eshipper, Parcelmix, Goshippo etc
Prestashop ----- Import/Export(CSV, XML) (15 + modules
Prestashop ----- Payment Gateways --- EBANX , ENETS, Barclays-ePDQ-Payment, Payrandom , Sparkasse ,Stripe etc. (15+)
Prestashop ----- Custom modules(20+)
1. Custom Order --- Module for Order management, instant Notification for Pizza delivery website
2. Auto Part finder --- Module for filtering every product list in the site using filters like (Make, Model, year),
3. Product Price Calculator --- Module to calculate Price based on the Formula created in the backend using Product attributes for Printing Website .
4. Order Scrapper from Email --- Module to automatic import order from the email by extracting content from the email data.
And many more