What Skills Make an eCommerce Developer Stand Out?

I've seen a lot of developers come and go on store projects, and the good ones usually share a few things. It's not always what you'd expect.
Here's what I'm looking for:

• Platform knowledge: Shopify, Magento and WooCommerce all work differently. Someone who has built on yours will save you weeks.
  
• Speed focus: A store that takes five seconds to load loses people fast. Good developers care about page speed and mobile layout.
  
• Checkout skills: Easy payment and fewer steps mean fewer abandoned carts.
  
• Integrations: Payment gateways, inventory tools, CRM or ERP. Linking them without breaking other things is a big plus.
  
• Security basics: SSL, PCI rules, safe logins. You don't want to learn this after a problem.
  
• Clean code: Easy to fix and grow later, not a mess the next person has to untangle.
  
• Clear communication: I'd take someone who explains things and warns me about delays over a genius who disappears for days.
  

If you're building something bigger, it can be worth it to hire dedicated ecommerce developers instead of juggling random freelancers. They get to know your store and goals, so you're not starting from zero every time. Checking past work and giving a small trial task first also helps a lot.
One more thing: pick someone who sticks around after launch. Stores always need fixes, updates and small tweaks.
What would you add to the list? Anything that made you pick one developer over another?