Boston-based Runkeeper, an app that lets users personalize and track workouts over time, is looking to break into the multi-billion-dollar fitness apparel industry with its own line of merchandise and partnerships with outside retailers.

Runkeeper has been testing its apparel venture for months and now has fully launched its e-commerce platform.

Until now, their limited edition cotton shirts could only be purchased by users who completed a weekly challenge, like running or walking three times a week. But only 5 to 7 percent of participants actually bought a commemorative shirt.

Now, you can buy one even if you never left your couch.

Boston native Jason Jacobs launched Runkeeper in 2006 and today it boasts a user base of 50 million. This gives Runkeeper access to a vast amount of consumer data, a valuable commodity for any business looking to boost its business.

The company has been struggling. In August, it laid off 16 employees — or 30 percent of its workforce — in a restructuring effort. In December, it hired former running apparel buyer at City Sports Katie Muldoon to spearhead the effort to boost the retail side.

Runkeeper currently has a feature that notifies runners when it’s time to buy a new pair of running shoes based on how many miles they’ve logged. In the near future, Jacobs said, the notification will come with a coupon for the brand of shoe the user wears.

Eventually, the company wants to be able to sell such merchandise on its website.

It’s one example of how the company hopes to use technology to gain a toehold in the competitive fitness apparel industry.

“It’s unclear who will be in the next wave of fitness companies, but it’s clear that whoever they are will be technology companies at their core,’’ Jacobs said. “Personalization has become a really powerful way to better serve the consumer, but also to sell more products.’’

Runkeeper has lots of heavy competition from fitness apparel behemoths like Nike and Under Armor. Nike netted over $30 billion in fiscal year 2015, and analysts estimate Under Armor generated $3.9 billion in revenue over the same period. Under Armor and Nike have their own fitness tracking apps. Under Armor has MyFitnessPal, which had 75 million users in 2014, and Endomondo, which had 20 million users in 2015. Nike’s ­Nike+, one of the first fitness trackers when it launched in 2006, had 28 million in 2014.

RunKeeper, a private company, declined to disclose earnings.

Jon Hurst, president of the Massachusetts Retail Association, said the company’s model is unique because it capitalizes on a market that’s already loyal to the Runkeeper brand. As online retailers continue to grapple with increasing competition and reduced market share, Hurst said that Runkeeper’s branded apparel is its best shot at winning over consumers.

“There’s so much competition and so many players,’’ said Hurst. “You have to create a niche in branding so folks can’t find a similar product elsewhere. You have to separate yourself.’’