A chatbot can now offer you protection against volatile airline prices. It’s the same bot, DoNotPay, that helped users protest parking tickets and even sue Equifax for small sums of money.

Joshua Browder, a junior at Stanford University, designed the new service on the bot in a few months, after experiencing rapidly fluctuating airline prices when flying to California during the wildfires last year.

“It annoyed me that every single flight, I could be paying sometimes double or even triple the person next to me in the same type of seat,” he told The Verge. Browder first used the service himself and then tested it among his friends in a closed beta. He claims that the average amount saved among the beta testers is $450 a year, though it’s not clear how many flights were booked and how much they cost.

The service is available to the public starting today. To use it, log in with a Google account, input your phone number, birthday, and credit card information through Stripe. (Browder swears the credit card information won’t be stored.) Then the chatbot tells you you’re all set. Now, every time you buy airline tickets, whether from an airline’s site or a third party, the chatbot will help make sure you pay the lowest price for your class and seat.

Browder gives the example of a person flying from New York to San Francisco on United Airlines. If the person books a $380 flight but the price then drops to $120, he claims the bot will negotiate with the airline behind the scenes, and the airline will then issue a $260 refund. And if “drastically cheaper flights exist at the same time you are leaving, it will ask you via SMS if you want to switch.”

The chatbot uses American rebooking rules on a ticket to switch flights and obtain refunds. It uses rules like the “24 hour rule,” weather warnings, and airline compliance with laws against price gouging to find cheaper tickets. Every five seconds, the chatbot checks for a deal up until the time of your departure, when weather and cancellation loopholes appear more often, according to Browder. DoNotPay actually books and holds the seat for you with its own money until your old seat can be canceled, using the bot’s VC funding.

Because it isn’t versed in other countries’ rebooking rules, the chatbot only works on US airlines with flights that depart from inside the US, whether domestic or international. It doesn’t work for flights flying from international into the US. (The chatbot can also check for lower hotel prices from five hotel chains, including Hilton, Intercontinental, Hyatt, Marriott and Best Western, but it doesn’t cover every hotel yet.)

Compared to its predecessors, the DoNotPay travel chatbot has a few improvements. Now, people don’t have to print out paperwork as they do when they wish to sue Equifax. The open-ended nature of the parking violations chatbot is also gone. Browder says that he listened to people’s feedback and tried to streamline the chatbot to make using it much simpler.

The app seems almost too easy and simple to use. Once you input all your information, the chatbot communicates with the airline every time you buy a ticket using the email address you’ve given the bot. The only communication you receive is from the chatbot via SMS asking whether you want the discount or not.

Browder says his chatbots will “always” remain a free product, but he does see a way to eventually make money off of these services. If this new flight feature proves to be popular, Browder will consider expanding it to “other industries like insurance, healthcare, and small businesses, where there may be more of an opportunity to make it commercially sustainable.”