During the last 12 months, traffic from consumers using iPad tablets to visit flash-sale retailer ideeli Inc.’s e-commerce site has increased 70%. Growth like that demanded a technology change to help the site load faster and make it easier to use on tablets, ideeli says.

Earlier this year ideeli revamped its e-commerce site using HTML5, an advanced web programming language supported by most mobile web browsers used on smartphones and tablets. The goal was to make it more appealing to shop the site from a mobile device.

“From an iPad perspective, it has been tremendous,” says Eduardo Frias, ideeli senior vice president of engineering. “We have seen a 70% increase in visits just from the iPad in a year. That drove additional revenue and a more than 25% increase in average order value.”  Between 10% and 20% of ideeli shoppers use an iPad, he says.

Ideeli’s adoption of HTML5 benefits the retailer in two ways, Frias says. One is that HTML5 can improve the page load times of mobile commerce sites by caching data within the mobile browser on the phone to speed page load times. That’s important for ideeli because of the influx of traffic when the daily sales go live, says Nick Tudor, ideeli vice president of architecture. Caching the data can potentially reduce the number of times a mobile browser has to ping ideeli’s database because part of the database is loaded into the browser, he says. “This makes our site very responsive for mobile users,” Tudor says. The first 15 minutes following the daily sale’s start time accounts for 15% of ideeli’s daily traffic, he adds.

The other benefit of HTML5 as the underlying technology for ideeli’s Internet site is it eliminates building and maintaining mobile and desktop sites using separate technologies, Frias says.

Many retailers like that aspect of HTML5, says Igor Faletski, CEO of Mobify, which helped ideeli create its site. “Retailers can invest once and reap the benefit across many devices,” Faletski says. “HTML5 allows a business to build on its existing infrastructure and existing web site to deliver touch points and make web sites feel more like apps.”

Ideeli is No. 172 in the Internet Retailer Top 500 Guide.