We've all been there: standing in a store at the holidays, product in your hand, absolutely dead positive you saw this same  purse/video game/DVD/emergency snake bite kit somewhere else and cheaper to boot. Was it online? Was it at Target or MegaloMart? And how much cheaper was it? A tiny bit not worth the effort or something totally on sale at such a price you'd knock over a senior citizen to get it? If only there were a way to check. Oh wait, you have your iPhone with you -- and boom, it's on.

RedLaser (Free)

While not one of the first to pop up under a search for "barcode scanner," RedLaser sits at 4.5 stars with 3052 ratings for the current version (alternately 4 stars cumulatively for all versions, with 56476 ratings under its belt). That's pretty impressive stats, and there's a reason for that. Only one other barcode scanning app comes even remotely close. Plus, at a price of free -- that's hard to beat.

RedLaser has becomes such a phenomenon that it even has its own SDK out there for developers who want to build it into their apps, and many have taken them up on it. But how does it stack up?

Use of the app is simple. Simply aim the iPhone camera at a UPC code, line up the little box on your screen with the outer edges of the UPC, and wait for the beep. We have to caution, though, this or any other barcode scanning app works far, far better on the 3G S iPhone 4 than on older models. The improved camera and autofocus of the newer handses make for better scans. We also can't recommend low lighting pictures or attempting to align your iPhone's (or newer iPod's) camera after you've drank one of the bigger cans of Red Bull.

RedLaser with Shaky Hands

Luckily, RedLaser (and the majority of other barcode related apps) allow for hand entry of UPC codes which can be quite a relief after you've sat there, camera in shaking hand, for five minutes trying to scan a can of Four Loko. Results for RedLaser's search are incredibly thorough, scanning through multiple sites including local results and even nearby libraries if the item you're scanning is a book, CD, or DVD.

RedLaser even excels at scanning the latest thing, QR codes. Small black and white pixel-ish square images that can prompt scanning devices to deliver nutritional data or direct you to a URL. Packing far more data into these little icons (1.8MB tops, and, remarkably, even video), they are not, however, something you can hand enter. Many retailers, especially in the fast food industry, have already begun using these, and we expect to see more of them as time goes on. One image scanned directly from a computer monitor even delivered a short message to phones in our test.

Hello back, Martin

It really is an app with virtually no drawbacks and smooth operation. Just stay off the Red Bull, unless you want to spend the day hand coding.

pic2shop (Free)

The other barcode scanning app with ratings in the tens of thousands, Vision Smarts' pic2shop is identically priced to RedLaser and, once again, offers a fairly similar array of services.

With a sporty red line you aim at UPC codes, this app delivers up the same type of online results, providing familiar big names (Amazon, Buy.com, and eBay) at the top followed up by  an array of lesser known e-vendors. While the app claims to pull local results, we were unable to get any of the items we scanned to deliver that kind of data even when we selected big box chains we knew were near us.

Unhelpful for Mac|Life Staffers

pic2shop was quite good about recognizing various products including hair conditioner, food products, kitty litter, though oddly a small electronic gizmo proved unknown to its system. There was also no support for QR codes, though this is something we imagine the developers are at work building in to a future update.

Lacking in local results for shopping, pic2shop does offer local library library results for items Dewey-cataloged and on the shelves. Whereas RedLaser offered up a page of info about the library results such as a link to the library website, its phone phone number and a link to a map, pic2shop only opened directly to the library catalog's results page based on your search. A map link would definitely prove useful in such situations, something the App Store page clearly indicates as a possibility for some local searches.

pic2shop Will Hook Your Kittens Up

The one element pic2shop does have baked into its results missing from RedLaser is in the Actions tab where you can query your friends on Facebook and Twitter about products you are looking for. Links direct users to a webpage identical to what users see inside the app. Longer named items will quickly eat up your tweet character limit and pic2shop didn't offer any easy way to correct this in its mobile Twitter interface. Using the same results page was pleasantly less intrusive in our minds than promotionally referencing via the app's Twitter account as some do.

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While neither RedLaser nor pic2shop has what we'd consider natively Apple quality beauty in their UIs, both offered pretty stripped down interfaces that got the job done. Both had issues with older cameras nabbing barcodes, though we'd give a minor edge to RedLaser in this respect. We'd also reward the app for the depth of its search and the fullness of its WorldCat library integration.

We don't necessarily see the value in the social sharing aspects of pic2shop's one additional feature, though we're not hugely social shopaholics ourselves. Times being what they are, we suspect that RedLaser will be putting some form of this into future builds. Both apps will likely converge toward near-identical offerings as time progresses, but at this point with its fuller search and its support for QR codes, RedLaser is the clear winner in this supermarket sweep.