A consultant who works from home wants to host a meeting somewhere with a professional atmosphere. A marketing VP traveling abroad wants a place to work other than the hotel lobby or a Starbucks. A software engineer wants a quiet spot to resolve office problems while on vacation.

Workspace-finding applications, such as Desktime, LiquidSpace, Loosecubes, and OpenDesks, are cropping up to help people in situations like these find good places to get things done. Some apps also help office owners fill extra space with people who have established a reputation for reliability.

Typically, a service can be accessed via either a website or a mobile reservation and payment app. These contain a catalog of temporary office spaces—some in dedicated shared work buildings, work-friendly coffee shops, and business centers, and others within the offices of startups or corporations that have unneeded space. Loosecubes, for example, offers about 1,800 spaces in 52 countries.

The apps aim to take advantage of the trend toward increasingly mobile workers. These days it’s not just freelancers, consultants, and the self-employed who go hunting for wireless signals with a laptop bag slung over one shoulder. Forty percent of IBM’s workforce works outside IBM real estate. The U.S. General Services Administration announced at the end of July that it will renovate its Washington, D.C., office building to accommodate about three times as many employees, mostly by eliminating private spaces and instituting a system whereby employees schedule desk space when they plan to come in to the office.

More than 10 million people in the United States are entirely mobile workers, with no permanent office space outside the home, estimates Chris DiFonzo, founder and CEO of OpenDesks. Adding in those who are mobile at least three times a month puts the number above 40 million.

For a time, many of these mobile workers parked themselves in coffee shops, but, DiFonzo says, “the café era is over.” For one thing, coffee shops nationwide have taken steps to discourage people from squatting for hours over tables and outlets. Workers might be better off finding new workspaces anyway, says Anthony Marinos of Loosecubes. “I don’t know if anyone ever liked working at coffee shops,” he says. “What do you do when you have to go to the bathroom? Do you pack up all your things every time? How often do you have to buy drinks?”

Marinos argues that shared office space not only is more practical but also can provide valuable social opportunities. For example, he says, instead of requesting informational interviews, perhaps recent college grads could spend a few days working in the offices of companies that interest them, where they would have a chance to make natural social connections with potential employers. Loosecubes itself opens its office to mobile workers, and recently partnered with a graphic designer it found that way.

However, to attract offices, apps have to offer a variety of amenities. “The extra spaces are still an outlier,” says DiFonzo, explaining that there’s still a lot of education and outreach to be done to persuade most companies to share their space with mobile workers.

While sharing space can bring in extra money for an office, many companies aren’t prepared for the headaches of managing mobile workers, says Sam Rosen, who runs Desktime. Apps need to help companies schedule their spaces, ask people for rent, and perform other vital tasks.

Mark Gilbreath, CEO of LiquidSpace, has taken this principle a step further. “Letting all manner of people use a space is a nonstarter in our minds,” he says. “Creating some form of trust mechanism is a critical requirement.”

LiquidSpace is designed to build up a set of credentials (a “passport”) for each user. Users must apply to a space for a “visa” to get access, or even to see if a spot is available. The system also waits until users have been approved and have arrived to release sensitive information such as door-access codes and Internet passwords.

Of course, the apps have to serve users’ needs as well. DiFonzo says that OpenDesks users divide into two groups: those who like to plan ahead and reserve spaces as they would in a hotel, and those who want something on the spot. He and other companies are building in mobile and social features to help users in both situations.

Most app developers believe that sharing office space can help businesses become more responsible and sustainable. “It’s about more than empty space,” says Rosen. “It’s about taking the space that we have and using it better.”

However, they agree that if this new way of working is to gain mainstream acceptance, it has to be convenient, inexpensive, and useful. Gilbreath, of LiquidSpace, says that workplace-finding apps need to give users a real-time solution when they need one: “I’m at the corner of Market and Third Street right now. I need to work for the next hour. Where can I work right now?”