We’ll find out soon if providers of online ordering technology are correct in saying that restaurant customers increasingly prefer to place orders via smart phones, tablets and computers instead of by fax and phone. But in the meantime, restaurant operators may want to monitor carefully how visible they are to customers who search for takeout and delivery food online. And there’s plenty to keep up with now that two online delivery giants plan to merge and a pair of smaller tech companies have found a way to target key subgroups of customers.

Given regulatory approval, the company that results from the proposed merger of Seamless and GrubHub claims its network will include 20,000 local restaurants in more than 500 cities. Last year, these two companies collectively sent $875 million in food sales to restaurants. Seamless and GrubHub are merging so they can grow their online ordering capabilities even further.

Some analysts suggest that the merger will also give the new company the ability to take on Yelp. Seamless and GrubHub both offer users the opportunity to rate and review restaurants and to read the reviews of others. Yelp still gets the lion’s share of online review traffic right now. However, Seamless and GrubHub offer online ordering capability in addition to providing reviews. Yelp does not.

Operators should also note that GrubHub owns Allmenus and Seamless owns MenuPages, two well-trafficked sites that provide welcome visibility for many restaurants whether they offer takeout or not.

GrubHub and Seamless take an everything-for-everybody approach. Some operators may be interested in exploring a more focused approach to online takeout and delivery orders.

One new company bases its service on the specific dietary needs of its customer base. San Francisco startup Hasty is introducing what it says is the first on-demand healthy food ordering app. It’s meant to appeal to restaurant customers who order food according to strict diet protocols such as paleo, low carb, gluten free and others. The iPhone app is still in beta testing and more than 20 San Francisco restaurants have already signed on.

"Our society has evolved to a place where eating unhealthy, processed fast food and pizza is convenient and cheap, and eating fresh, healthy food requires a lot of effort, planning and expense,” says Hasty founder and c.e.o. David Langer. “People want to take more control of what they're putting in their body. Creating a convenient, affordable way to eat healthy food, anytime, anywhere, will transform lives."

Early results show that “power users” use Hasty to order meals two or three times each week. Even if your restaurant features just a handful of healthful items on its menu, a service like Hasty would give healthful meal seekers a way to cut through the online clutter to find what they want at your restaurant.

In New Orleans, www.IMustEat.com is taking a localized approach to the restaurant online ordering guide business. Its site is limited to New Orleans restaurants and the company says it focuses on the true cuisine of New Orleans. Approximately 50 restaurants already use this service, ranging from local institutions like the legendary Acme Oyster House to chain operations such as Landry’s Seafood.

What’s in it for restaurant operators? Plenty, the IMustEat people claim.

“There are no upfront costs and no monthly charges,” says a company release. “Many of the IMustEat restaurants have gained new followings and loyalty. IMustEat allows a restaurant to see who its customers are, what areas in town are most responsive, what time of day works best, etc. This allows a restaurant to work with IMustEat and hone its message to the audience that returns the most in ticket size and frequency of orders."

Online ordering is a fast-developing field and we don’t know whether recent moves by Seamless/GrubHub, Hasty or IMustEat will turn out to be true game-changers. But it’s got to be a good thing that more companies are venturing out into cyberspace to drum up additional business for your restaurant. We can’t tell you which service provider you might want to hook up with, but we can say that it looks like many restaurants could soon have a larger takeout and delivery component than they once did. Prepare accordingly.