When I’m looking online for verses and concordance searches, I use two main sites:
The NET Bible. The verse search has multiple versions, plus Greek. And there’s a Firefox search add-on for this site, so I plop a verse in the search box, choose NET and it’s there.
Sometimes I want to do a word search in just the NT. I love this site, uses the ESV as base text. No clicking for the next page of verses. It’s all there on one page.