To hear Grier Allen tell it, BoomTown's first office in the old Faber House on East Bay Street had rats.

Now several years on, the CEO's workspace has a cinder block and glass brick wall and was once the seafood section of the former Jaber's Market on Rutledge Avenue.

Moving a little over a mile in seven years, from live rodents to fish souls, might not scream success.

But Allen likes where he and his real estate software firm are. That's because BoomTown has been covering ground in other ways. You might even say business is booming.

Revenue is on the rise as more brokerages buy more of BoomTown's software and services. And so is the company headcount, leading to a series of expansions of the company's headquarters, the latest coming this month.

Allen's profile has risen simultaneously as a member of Charleston's new vanguard of tech entrepreneurs. He was invited to present last month at a venture capital conference in Charlotte and will appear on a panel this coming weekend at the inaugural DIG SOUTH Interactive Festival downtown.

"It's just a fun time right now," said the 33-year-old Summerville native, who sported a camel hair jacket with jeans during an interview last week.

When faxing leads to coding

At its root, BoomTown is a product of Allen's family background in real estate and his personal bent toward code.

While he was finishing up a computer science degree at Clemson (BoomTown's colors are orange and blue), Allen interned at his father's Prudential Carolina (now Carolina One) office. Charged initially with manning the fax machine, Allen tried his hand at writing computer code that would automate some of the office's business.

That led to postgraduate work as a consultant, and after co-founding and leading SLANT Media for a couple of years, Allen teamed up with Cooper Bane to start BoomTown in 2006.

With Allen's brother, Robertson's, local brokerage, The Cassina Group, as its guinea pig, BoomTown developed its lead-generation software. (The brothers live two doors down from each other in Mount Pleasant and frequently talk shop, Grier said.)

The resulting technology suite and strategy has several components, but the basic idea is to attract home shoppers from the Internet and funnel them to local brokers so they can close the deal.

Paid search advertising and search engine optimization strategies bring prospective homebuyers to the broker's BoomTown-run website, and then the back-end software helps log, organize and present all shopper activity on the site.

"We're tracking every time you look at a property," Allen said.

The broker then gets a list of leads, rich with information about the shopper's preferences and tendencies, which streamlines his sales efforts. A new feature for which BoomTown has filed a patent application presents brokers with a priority list of prospective buyers who might include someone who made a property a favorite because it just went down in price or someone who was shopping intensively months ago and now is back on the site.

"What's your next dollar-predictive activity?" Allen said in broker lingo. "The Opportunity Wall tries to answer that question."

BoomTown has expanded to some 600 brokerages around the United States and Canada. The company recently began selling so-called inbound marketing services, which means writing newsy content for brokerages' websites in the hope of attracting web traffic from search engines and then customers.

It's all part of a 21st-century approach to real estate, one where human interaction still matters but where software makes those connections possible.

"The technology has sort of changed the game," Allen said. And BoomTown seems to be winning.

Money talks

In 2008, BoomTown's revenues were $145,000; in 2011, the top line was $4.6 million; and last year, the figure eclipsed $8 million. That trajectory made BoomTown the second-fastest-growing private company in South Carolina last year, according to Inc. magazine.

From just a few guys in its early years, BoomTown had grown to 38 employees by 2011 and now counts more than 80 people on the payroll. The plan is be more than 110 strong by the end of the year and perhaps double its size by the end of next year.

To keep pace, the company has taken over the erstwhile Jaber's building just south of Hampton Park and transformed it into a contemporary tech office, featuring lots of computer screens but also scooters and a dog park out back.

Already in Suites 104, 105 and 107, BoomTown's next expansion will be into Suite 106, the 5,000 square feet recently vacated by pharmacy program management company Equiscript. Work on the new space is scheduled to start in the next few weeks.

And to sustain the business growth, BoomTown has moved into serving listing agents, too.

"In the bad times, they need buyer leads," Allen said. "In the good times, they need seller leads and buyer leads."

BoomTown has competitors, from giants like Zillow to smaller, cheaper upstarts, but Allen insists BoomTown just needs to execute its plan to continue its success. (The lack of parking for all its new employees is perhaps a more pressing concern.)

And those in the know seem to agree, Allen said.

At the Southeast Venture Conference in Charlotte, the money guys were quite receptive, Allen said, noting real estate technology and advertising is a $13 billion market.

"Real estate is very ripe for disruption right now," Allen said. "Ninety-plus percent of people are searching for their homes on the Internet. Everyone's trying to figure out a way to capitalize on that opportunity."

BoomTown, which is self-funded, doesn't need or want outside money now, he said. But he keeps in touch with potential investors just in case the company decides to go that route.

Plus, "It's fun to tell the story," he said.