Best Firefox extensions: Shopping spree

InvisibleHand can help you compare prices across sites.

This is the third installment of our series of reviews of Firefox extensions. We've broken the vast array of extensions available for the open source browser into a number of categories, and picked the best extensions in each category based on a weighted formula that takes into account ratings, number of reviews, and total number of downloads as of December 29, 2010. In this installment, we'll consider the extensions that Mozilla puts in its Shopping category.

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In spite of the recession, or perhaps because of it, online shopping is more popular than ever. Depending on who's counting, estimates indicate that 2010 online shopping was up anywhere from 11 to 25 percent over 2009. And while online shopping is still only a fraction of in-store shopping, with that kind of growth, this may not last.

With so many shopping choices out there, it's important to have the tools that you need to get the best values. That's what the extensions in this Shopping category are all about. We realize that most of these add-ons will be variations on a theme, but let's do the comparison, shall we?

Amazon Toolbar This extension provides the Amazon Hot Stuff toolbar, which acts as a meta-navigational aid for If you do a lot of shopping on that site alone, I can see where this would be useful, since it has search, navigation, and account management tools built in. If you shop at more sites than just Amazon, then it is a bit limited.

AmazonAssist. Even though this is the official Amazon extension, right off the bat I have some concerns with it. When the add-on is installed, it asks permission to follow your web site surfing and use that information to personalize your Amazon shopping experience. Even though this is only done if the extension is active, it still gives me the heebie-jeebies. I can see where this would be a good idea on paper, but that's a lot of potential privacy issues to wade through. Beyond this functionality, the add-on provides the usual navigation tools, albeit it as a menu button on top and a search bar on the bottom of the browser, which is less than optimal. You will need to decide for yourself how much you want this extension to delve into your browsing history if you are looking to download it.

Dynamite Deals. Dynamite Deals is a sit-back-and-pounce type of add-on. It waits patiently for you to land on a product page on a shopping site somewhere, and then -- boom! -- it will give you a (hopefully) lower price for the same item on another site. This worked as advertised, but when it reported lower prices for an electric razor and remote control toy I found, the prices on the other retailer were out of date and therefore wrong. It also reported a higher price for the laptop I was looking at, which, I suppose, is just as useful, since that meant the page that I was on potentially had the lowest cost. Still, you think it would be smart enough to recognize that and tell me that for sure. It was not clear which retail sites this extension was polling, nor could I set that in the options. I don't think this is a strong contender.

eBay Sidebar. As, the official eBay extension for Firefox, you would expect this to be a killer add-on for the auction site, and I have to say it didn't disappoint. Bid on anything on eBay, and the sidebar will automatically keep track of the item for you. The same is true for items you're auctioning off. The account management tools are where this add-on really shines, allowing you to manage anything you normally would on the eBay. There's even a connection to PayPal, the payment site used for the venerable auction site. If you spend any time with transactions on eBay, you can definitely use this extension.

InvisibleHand. Another product comparison extension, InvisibleHand works a bit differently than Dynamite Deals. Instead of sending in a pop-up message automatically, you have to click the status bar icon to get the pop-up bar to show up. Performance-wise, this was a faster and more complete comparison tool than Dynamite Deals. It gave me multiple retailer results for the same three test products, and informed me when one of my products was indeed the cheapest. Even though it's not proactive, the value is the thing, and InvisibleHand delivers that well.

Offer Assistant. Offer Assistant stands out in this category if only because it doesn't do price comparison. What it does do is track your shipping and billing information so that when you get to the checkout page of any commerce site, you can have it auto-fill your information. This time-saver alone makes the extension worth using, but here's the real value: Offer Assistant also informs you if any product you're looking at has a discount promotional code associated with it. I think about all those times I looked longingly at those promotional code fields and it makes me all a-flutter to think I might actually have something to enter there.

PriceBlink. Another price comparison tool, PriceBlink proactively jumps in and gives you information on what other retailers are charging for the same product. It didn't do quite as well as InvisibleHand, though, missing the best price on the razor, though accurately reporting the best prices for the laptop and the toy. That could be forgiven, because of the extra value-add PriceBlink potentially brings: it can list specials and online promotional codes that might apply to your purchase for the site. It doesn't do that for every product, of course, so you will need to weigh your options.

PriceGong. Unfortunately, PriceGong takes the approach that if it can't find the exact product you're looking at, it will just toss up another product that seems close. This results in pop-up windows that are often comical, since apparently it hasn't occurred to PriceGong that not all similarly sized laptops are even close to being equal. On products it was able to match, this extension just plastered up the pop-up window even if the price was much higher on the suggested site. This seems to be a shopping app designed to steer consumers to sponsoring sites, and that's pretty much it. I would give this one a miss.

PriceTrace. PriceTrace has set itself up as a full-blown toolbar, complete with a search field to find items you are looking for right from the start, which is useful. You can also click a button to compare prices on the product in the open tab/window. The response rate was very slow, but based on some tests, I think it was an overall server issue, rather than the service itself. PriceTrace was very accurate with its comparisons, and while it doesn't track promotional codes, it does provide a nice price tracking system that will e-mail you if the price goes down. If you're not in a hurry, then this is a sweet feature.

WindowShopper. WindowShopper has very little up its electronic sleeves to differentiate it from the other comparison extensions, save this: it will happily tap into the Amazon Marketplace to find a better deal, something the other add-ons don't typically do. This meant that it was able to find deals on a par with InvisibleHand's and PriceTrace's searches, just in a different place. But it blew the laptop search, telling me a retailer had the device for $30 less ... when I was actually on the same retailer's site. I saw some beta labels floating around this extension, so definitely updated pricing is going to be a big fix before it goes to gold.

Comparing the price comparison tools, I have to give nods to InvisibleHand and PriceTrace for best price searching, though InvisibleHand was a lot faster. PriceTrace gets points for the price tracking feature, and PriceBlink, though it wasn't as accurate, gets a thumbs up for handling specials and online tools.

Up next: Sound and fury

The days of the browser as a delivery vehicle for just text and images are long over. The next installment of this series will focus on Firefox extensions that deal with multimedia content.

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