Have you ever kicked yourself for paying full price only to discover that the boots you bought were on sale for $25 less on another retailer’s site? Or they got marked down on the same site three weeks after you hit the “buy” button? Or you realize later you forgot to check if there were coupons you could have used?

Sure, you can go through the trouble of returning an item and buying it for less on another site. (Although you may pay as much on shipping.) And you can call a retailer and try to get a credit for the difference when an item goes on sale after you bought it, or see if you can apply a code retroactively (good luck).

Or you can turn to these five apps and browser extensions, which will do that work for you. And you can set it, forget it—and save.

1. Honey

You probably know that it pays to search the web for coupon codes before completing an online purchase, but doing so is usually pretty time-consuming. Plus, you might scour various sites, only to find that none of the coupons actually work.

Enter Honey. This browser extension for Chrome, Firefox, and Opera sources coupon codes on your behalf—from retailers like Amazon and Walgreens to J.Crew and DSW—and determines which one will save you the most. Depending on what deals are available when you’re shopping, Honey can potentially help you score free shipping, 30% off your order, or even bigger savings.

2. Paribus

Many retailers will offer a price adjustment if something you bought drops in price within a certain timeframe; but, chances are, you aren’t keeping track. Paribus automates this process by scanning your email account for purchase confirmations from big retailers like Amazon, Macy’s, and Best Buy, notifying you when something goes on sale, and then requesting a price adjustment on your behalf.

Thanks to Paribus, you can expect to save anywhere from a couple bucks to upwards of $30 per price adjustment without lifting a finger. (Although Paribus will take a 25% cut—or less if you refer others who install the app.)

3. Invisible Hand

This Firefox, Chrome, and Safari extension provides a pop-up notification when something you’re looking at online is sold for less on another site. “I find it’s incredibly helpful in pointing out a cheaper price,” says consumer and money-saving expert Andrea Woroch. “Especially when I’m searching sites like Amazon that I automatically assume has the best deal.”

Savings vary depending on what you’re buying, but you can count on at least a few bucks each time the pop-up appears. It’s also helpful for travel, since it not only works with retailers, but hundreds of airlines, too.

4. CouponSherpa

According to Woroch, this app never fails to help her find a deal while she’s already out shopping. That’s because one of the ways CouponSherpa helps shoppers save is by using location data to serve up coupons for nearby stores. You can also earmark or search for your favorite retailers to find out what deals are available at any given time. And you never have to print or clip the coupons—the cashier can scan it directly from your phone.

Last time we checked, there were coupons available for 60% off at Office Depot, a free rental day from Hertz, and 30% off your entire purchase at Gap.

5. Trim

Yes, this app won’t help you when you’re shopping. But it can keep you from paying for subscription services or products you no longer want. Ever signed up for free trials and totally forgotten to cancel them, even after the charges start rolling in? Add in a forgotten music service or old premium subscription, and you could be shelling out a good chunk of change each month without even realizing it.

Trim will pinpoint monthly subscriptions on your credit card or bank statements and cancel the ones you don’t want. This way, you’re not paying for more services than you use, and you don’t have to go through the hassle of figuring out how to opt out.

Photo of person shopping online courtesy of www.patrickbraun.net/Getty Images.