No, it’s not your imagination. The rise of COVID-19 has brought a big drop-off in those annoying robocalls.

According to YouMail, which makes a popular robocall blocker, US consumers got 4.1 billion such calls in March, down from 5.2 billion a year earlier. Credit the epidemic, which shut down many of the sleazy outfits that generate these calls. But as the world beats back the coronavirus, can we expect a resurgence of the robocall plague?

Not if Joshua Browder can help it.

The British-born, Stanford-trained software engineer doesn’t just want to stop those infuriating calls; he wants the callers to suffer as we have suffered, and maybe a little more. Browder wants revenge, and he has written some software that’s designed to get it.

Called Robo Revenge, it’s included in the iPhone-only app DoNotPay. Robo Revenge helps users file lawsuits against robocallers by tricking them into revealing the source of the unwanted calls. “Instead of them scamming you,’’ Browder said, “you’re scamming them.’’

It’s not a completely nutty idea, and it comes from a man who’d probably be a crackerjack attorney if he wasn’t so busy writing code.

Under the Telephone Consumer Protection Act of 1991, consumers have a right to sue marketers who phone without permission. Win your case, and the offending company must pay you $500 per call, an amount that triples to $1,500 if you show that the caller should have known not to dial you up. If you’ve listed your phone on the federal Do Not Call list and a robocaller dials your number anyway, you can demand payment, and sue in small claims court if the robocaller doesn’t mail you a check.

But how do you find the source of the robocalls? These people use computer-generated “spoof’’ numbers with no connection to an actual address.

Robo Revenge solves the mystery by giving you a temporary credit card number that you provide to the robocaller when he tries to sell you something. When the robocaller tries to collect the money, the card is rejected. Even so, the attempted transaction is sent through the credit card network.

To collect the payment, the scammer has to provide a name, address, and phone number to the credit card processing company. Even though the card is worthless, the information is relayed to DoNotPay, which shares it with you. So now you know whom to sue.

The app generates a letter demanding that the robocall company pay the legally mandated penalty, or face a showdown in court. You print out the letter, mail it to the phone spammer, and wait. Browder says that early adopters of his app haven’t had to sue; settlement checks just show up in the mail, some in as little as one week.

Robo Revenge is just one feature of DoNotPay, an app born of Browder’s terrible parking habits. Back in the United Kingdom, he ran up about two dozen parking tickets. He couldn’t find the cash to pay them, but he learned that many tickets could easily be beaten through some legal technicality. So Browder wrote a software program to generate automatic appeals, with no need for court appearances. Browder’s program worked about 50 percent of the time, saving him a few hundred British pounds.

When Browder arrived at Stanford in 2015, he turned his idea into DoNotPay — “the world’s first robot lawyer,’’ as he calls it. “It started out helping people get out of parking tickets,’’ Browder said, “and it’s expanded into 100 different functions.’’

Yes, it will appeal US parking tickets. But DoNotPay can also rebook your airline flight if a cheaper fare comes along. It can get you an appointment with the Registry of Motor Vehicles to take a driving test. And you know those online subscriptions that offer the first month for free, but ask for your credit card number? DoNotPay can generate a temporary credit card number for you. When the month is up, and the company tries to start charging you, too bad. The DoNotPay credit card won’t accept charges, so you’re off the hook.

Yet another feature, called Digital Health, will automatically contact Equifax and dozens of similar data brokers that collect sensitive information about you. Digital Health will help you see what data these companies have collected and can automatically issue a demand that they erase it all.

The full suite of DoNotPay services costs $3 a month. The app has attracted about 100,000 users, as well as $5.7 million in venture funding. Browder has dropped out of Stanford to focus on turning DoNotPay into a paying business. But given our hatred of unwanted calls, the app’s new Robo Revenge feature could make Browder a rich man all by itself, if only it worked.

Robo Revenge won’t help against robocallers based outside of the United States, beyond the reach of our laws. Next, what if the caller doesn’t ask for a credit card?

For instance, I was recently pitched by a New Hampshire home improvement company offering free estimates on siding. They just wanted my address.

Other scammers want only your Social Security number — for use in identity theft. In these cases, Robo Revenge is useless.

Besides, if you go to court, you might not win. Aaron Foss, creator of the robocall-blocking program Nomorobo, says that even if you took a robocaller to court, it would deny making the calls. It would be hard and costly to prove the lie.

In addition, Robo Revenge supplies the robocaller your name and address, to go along with the phone number. If you won a large enough judgment against the company, the money would be taxable, and you’d have to provide your Social Security number. Now these guys know everything about you. And they’re criminals.

“These guys can very easily retaliate,’’ Foss said. “It’s a dangerous, dangerous game to play.’’

Browder replies that you can set up Robo Revenge to use a post office box number instead of your actual address. He also argues that companies would face even stiffer penalties if they attempted to retaliate. But then you’d have to prove that they’re victimizing you, and they won’t make it easy.

And if you win a judgment, how do you get paid? Even the federal government hasn’t managed that trick. The Wall Street Journal reported last year that the Federal Communications Commission has fined robocallers more than $208 million since 2015. The agency has collected just under $6,800. And no, that’s not a typo.

Maybe they’d have better luck simply by shutting the robocallers down — even the foreign ones, which rely on US companies to reach us. In February, the Justice Department sued two US companies that deliver these foreign calls, and the FCC sent warning letters to seven more US firms.

Meanwhile, a federal law enacted last year requires the nation’s major phone companies to install technology that does a better job of identifying phone spam, and blocking it before your phone even rings.

It took years to solve the spam e-mail problem. Wiping out robocalls will prove just as challenging.

And despite Joshua Browder’s best efforts, there isn’t an app for that.

Hiawatha Bray can be reached at Follow him on Twitter @GlobeTechLab.