BELLEVUE, Wash. — The offices of OfferUp in the suburbs of Seattle are decorated with the kind of offbeat knickknacks that are easy to find on an online classifieds site like Craigslist.
There’s a large Yoda statue, a Victorian settee and a table made out of the wood from a bowling alley.
All the items, though, were purchased through OfferUp’s own local Internet marketplace, a fast-growing alternative to Craigslist that is innovating in areas that have long been neglected by its much bigger rival, like mobile and mechanisms for making buyers and sellers more comfortable with each other.
And now after a period of lying low, OfferUp has begun to talk publicly about the growth of its local marketplace and the war chest it has built up to take on Craigslist. In March, the company quietly raised $73 million in a funding round led by T. Rowe Price Associates, along with Andreessen Horowitz, Coatue Management, Tiger Global Management, Vy Capital, High Line Venture Partners and Allen & Company. (Word of that fund-raising has circulated for months.) That brings to more than $90 million the total amount OfferUp has raised.
Founded in 2011 by Nick Huzar and Arean van Veelen, the company’s chief executive and chief technology officer, OfferUp has expanded its local listing service from the Seattle area to every major city in the United States. In an interview in the company’s offices earlier this week, Mr. Huzar said OfferUp had racked up $2.9 billion in transactions so far in 2015.
The value of all items being sold through the service is now five times what it was at the beginning of the year, the company said. Cars, furniture and toys are all big categories on OfferUp.
The company, which had 15 employees a year ago, now has 67. There have been more than 12 million downloads of the OfferUp app. A year ago, that figure was 1.5 million.
Craigslist has been the go-to site for selling items people no longer want, but it hasn’t evolved a whole lot since it was created in the 1990s.
“Craigslist never really invested in the user experience,” said Jeff Jordan, a partner at Andreessen Horowitz and an OfferUp board member. “They don’t have a mobile app. The site hasn’t fundamentally changed in a decade.”
(Mr. Jordan is a former executive at eBay, which was involved in a long-running legal battle with Craigslist that ended in June after eBay agreed to sell a 28.4 percent stake in Craigslist back to the site.)
Jim Buckmaster, the chief executive of Craigslist, didn’t respond to an emailed request for a comment.
The smartphone is central to OfferUp’s belief that it can make listing items for sale a lot easier than on Craigslist. You snap a picture of the item you want to sell directly in the company’s mobile app and post the listing with a few more taps.
The company has also designed the service to help buyers and sellers trust each other more. OfferUp users have profiles and can be rated by people they have completed transactions with. OfferUp has an optional service called TruYou, through which users allow OfferUp to verify who they are after they scan in their identification cards.
There are a bunch of other local marketplaces attacking Craigslist with mobile services, though it’s unclear whether any of them will ever grow as big. A Canadian start-up called VarageSale raised $34 million from venture capitalists this year, and eBay has created a local listing service called Close5 that has landed on the most downloaded charts in mobile app stores.
Mr. Huzar said OfferUp wanted to reach the many people he believes do not buy or sell through Craigslist because of the hassles of the site. “We said, ‘Yeah, Craigslist was the 800-pound gorilla in the room,’ ” Mr. Huzar said. “But we felt there was a much bigger market out there.”
One thing worth pointing out is that OfferUp is making no revenue, since it is not charging a transaction fee. The company’s executives won’t say how and when it plans to begin charging its users.
One of the big attractions of Craigslist is that its listings are free in most categories. Mr. Huzar argues that there are still costs to using the site, even if it doesn’t pull money directly out of people’s pockets.
“I would argue that it isn’t free,” he said. “What’s your time worth? What’s peace of mind and trustworthiness worth?”