Now, people will do a quick browse from a smartphone while on the move, then shift to a tablet while sitting in front of the TV and finally make a purchase from a laptop. Consumers expect shopping sites to adapt to their use of technology, but the older CDN services were built for a PC-centric world.  "We were desperate to find another solution," said Greg Tatem, Wine.com's vice president of engineering. "This isn't about just one device anymore, and not just about mobile. We have to completely rethink that paradigm."  For Instart, Wine.com was a very early customer. The Palo Alto, California-based company has since grown so fast that investors like Andreessen Horowitz, Greylock Partners and Kleiner Perkins Caufield & Byers have been pouring in money, including a $26 million financing round in May.  This is only the second holiday season for Instart since its public launch in mid-2013. The company now has about 100 customers, with 90 percent in online retail, said its founder and chief executive officer, Manav Mital. They include Dollar Shave Club, One Kings Lane and Stella & Dot. Washington Post is also a client.  Read More'Boring' Akamai hot tech play  Taking on market leader Akamai is no easy task, and if CNBC.com's series "Powering the holidays" were all about the biggest technology players, Akamai would capture most of the CDN ink. The Cambridge, Massachusetts-based company, founded in 1998, generated more than $1.5 billion in revenue last year and has more than 150,000 servers in 92 countries. Best Buy, L'Oreal, Microsoft and Staples.com are among the many large brands that count on Akamai to speedily delivery traffic to their sites.  Given that 15 to 30 percent of Web traffic flows through Akamai, the company has an added security layer because it has seen many of the most sophisticated cyberattacks and can react accordingly. And for the first time, through a partnership with Cisco, Akamai is bringing its technology into stores, powering digital signage and product recommendations for retailers like Louis Vuitton.  The company feels it handles the habits of the multiplatform shopper just fine.  "We have a very broad set of capabilities that really address customer problems in three different segments," said Neil Cohen, an Akamai vice president. Last year on Cyber Monday, the company's network saw 11.2 million page views per minute at its peak. "When retailers need us the most, we deliver at scale for all of our customers," Cohen said.  Read MoreDollar Shave's razor strategy  As if going up against Akamai wasn't enough, Instart is also taking on Amazon.com, which has a product called CloudFront that's part of its fast-growing cloud services business.  But Instart has one big advantage over most enterprise software start-ups that are trying to displace established incumbents: It takes almost no time to switch. Companies don't have to implement a big software suite and get employees trained on new tools. Rather, they just redirect how traffic comes to their site and within a few minutes, they start seeing the results.  "Switching costs are shockingly low," said Mital, who started the company in 2010, after stints at Yahoo and Aster Data, which was acquired by Teradata. With that, "we make sure we enable the delivery of the best possible experience to users across devices."
Because consumers can click to another site or app to make their purchases, the Web buying experience has to be clean, fast and fun.