I can't see them in the source code.
The likely answer is you won't. Most modern eCommerce websites use a "Container Tag" to house their many tags/pixels.
If you look at the source code and you are lucky, you might see the container, but no trace of your tag.
To see all the things that your browser (Firefox, IE, Chrome, Safari) is making, you need something extra. A plugin if you will.
There are many tools for the job; HTTPwatch, Tamper Data, Httpfox, Ghostery, Fiddler2 to name but a few. In order to compare the best, let's first get rid of the worst.
Tamper Data - It's too hardcore. Amazing if you need to alter POST data on the fly, but useless to the average user.
Exclusive to Firefox, this extension also lacks an export function, so you'll struggle to show anyone else your good work.
Fiddler2 - Apart from sounding ike an inappropriate Batman villain, Fiddler has a larger issue. It lies! When looking for tags you need a tool that will show requests from the Browser not the computer. This is because tracking is all about browser cookies. If the tag has been implemented in a strange way (say incorrectly via Flash) Fiddler can give false positives, thus false hope. Fiddler is good for many things, but don't always trust it when it says your tags are present.
Only the best appear below. Ranked in order of greatness, considering ease of use, output options and cross browser compatability.
3. Ghostery - This is the easiest to use and most compatible plugin of them all. Simply install Ghostery for either Firefox, IE, Chrome or Safari and you'll have a rough idea of what tags are where. When running (always on by default) Ghostery will overlay a purple box on top of the webpage, identifying tracking tags by company (Google Analytics, DoubleClick etc.).
Ghostery is designed to "reveal" to the consumer the horrid and deplorable "tracking bugs" that infest web pages. It's pretty good at instilling fear into the average consumer, and if you are not scared, it makes for a pretty nifty tag sniffer.
Here you can see Ghostery in action. The reason this tool comes in at number 3 is the fact you can't really see any information about the tags other than the company. You can't see what values are being given to the tag, or even what the tag name might be.
There is a hidden toolbar, and if you can see it, you can click on the red ghost to find out more about certain tags, but it doesn't always work, so I'm discounting it.
What Ghostery is very good for is revealing what publishers your competitors are using. Simply navigate to your competitor's homepage and a whole host of pixels will be revealed, indicating which publishers are likely receiving cold hard cash from your competitors.
2. HttpFox - This plugin is simply amazing. A Firefox-only plugin this addon will work on Windows and Mac, making it number 1 for all the mac users reading this.
HttpFox (download here) shows every HTTP request that your browser makes. This means that you will see every image, asset and tag that your browser loads. It will tell you if the connection was successful, if the security certificate is invalid and will even let you filter. So for example if you are trying to find all the Mediaplex tags on your website, simply type "mediaplex.com" into the HttpFox search box, and it will only show browser requests to Mediaplex.
It's not the prettiest thing to look at, and export options are limited (you have to "copy all rows" and then paste into Excel). That said, it's super easy to use for tag finding so anyone from traffic manager to planner can get in on the action.
For the power user HttpFox is open source under the GNU GPL v2 license. The source code is available here and written entirely in XUL plus JavaScript makes it very easy to tinker with. The ability to re-purpose HttpFox into a slimmer more specialised tag sniffer makes it a firm favourite at number 2.
1. HTTPwatch Basic - the self confessed king of the tag finding tools. This plugin comes in 2 variants (Basic and Professional) and is available for both IE and Firefox.
The basic version is free and available for download here. The Professional version will set you back £259, but there is no need to buy this.
Open HTTPwatch within the browser, hit the big red Record button and you are good to go. You can filter the output on URL, type, response, even set AND/OR filters. For example filtering: URL contains "mediaplex.com" AND type is "image/*" so this will only show image pixels from Mediaplex. You can then navigate around your clients website and when you reach a page that is tagged, a new row will appear in HTTPwatch.
Should you need to save the output you can save as a HTTPwatch Studio File (.hwl). This lets you email it to another HTTPwatch user and they can see the output exactly as you saw it. Filters can be retrospectively applied, and you can quickly jump to a page by right clicking in HTTPwatch and selecting "Open URL in new Tab".
A final handy feature is the Time Charts. This gives you a rough idea of how the page loads, and makes clear any element of a page that takes too long. This is the ideal tool for discrepancy analysis since you can see at what point in your tag began loading. Sometimes you will see a page load other elements for 30 seconds before it even gets round to your tag. In this case it's time to ask the developer to move your tag closer to the top of the page.
HTTPwatch is the best Tag Finding Tool because it's incredibly easy to use as a planner or trafficker. On top of that the raw data is preserved in the .hwl file, so that when you pass on the file to someone more technical, there is still lots more for them to look at.
HTTPwatch... if only they made you for Mac!
