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Openpixel is a customizable JavaScript library for building tracking pixels. Openpixel uses the latest technologies available with fall back support for older browsers. For example is the browser supports web beacons, openpixel will send a web beacon, if it doesn't support them it will inject a 1x1 gif into the page with tracking information as part of the images get request.

At Dockwa we built openpixel to solve our own problems of implementing a tracking service that our marinas could put on their website to track traffic and attribution to the reservations coming through our platform.

Openpixel handles the hard things about building a tracking library so you don't have to. It handles things like tracking unique users with cookies, tracking utm tags and persisting them to that users session, getting all of the information about the clients browser and device, and many other neat tricks for performant and accurate analytics.

Openpixel has two parts, the snippet (snippet.html), and the core (openpixel.min.js).


The openpixel snippet (found at src/snippet.html) is the HTML code that will be put onto any webpage that will be reporting analytics. For Dockwa, our marina websites put this on every page of their website so that it would load the JS to execute beacons back to a tracking server. The snippet can be placed anywhere on the page and it will load the core openpixel JS asynchronously. To be accurate, the first part of the snippet gets the timestamp as soon as it is loaded, applies an ID (just like a Google analytics ID, to be determined by you), and ques up a "pageload" event that will be sent as soon as the core JS has asynchronously loaded.

The snippet handles things like making sure the core JavaScript will always be loaded async and is cache busted ever 24 hours so you can update the core and have customers using the updates withing the next day.


The openpixel core (found at src/openpixel.min.js) is the JavaScript code that that the snippet loads asynchronously onto the clients website. The core is what does all of the heavy lifting. The core handles settings cookies, collecting utms, and of course sending beacons and tracking pixels of data when events are called.


There are 2 automatic events, the pageload event which is sent as the main event when a page is loaded, you could consider it to be a "hit". The other event is pageclose and this is sent when the pages is closed or navigated away from. For example, to calculate how long a user viewed a page, you could calculate the difference between the timestamps on pageload and pageclose and those timestamps will be accurate because they are triggered on the client side when the events actually happened.

Openpixel is flexible with events though, you can make calls to any events with any data you want to be sent with the beacon. Whenever an event is called, it sends a beacon just like the other beacons that have a timestamp and everything else. Here is an example of a custom event being called. Note: In this case we are using the opix function name but this will be custom based on your build of openpixel.

opix('event', 'reservation_requested')

You can also pass a string or json as the third parameter to send other data with the event.

opix('event', 'reservation_requested', {someData: 1, otherData: 'cool'})
opix('event', 'reservation_requested', {someData: 1, otherData: 'cool'})

You can also add an attribute to any HTML element that will automatically fire the event on click.

<button data-opix-event="special-button-click">Some Special Button</button>

Setup and Customize

Openpixel needs to be customized for your needs before you can start using it. Luckily for you it is really easy to do.

  1. Make sure you have node.js installed on your computer.
  2. Install openpixel npm i openpixel
  3. Install the dependencies for compiling openpixel via the command line with npm install
  4. Update the variables at the top of the gulpfile.js for your custom configurations. Each configuration has comments explaining it.
  5. Run gulp via the command npm run build.

The core files and the snippet are located under the src/ directory. If you are working on those files you can run npm run watch and that will watch for any files changed in the src/ directory and rerun gulp to recompile these files and drop them in the dist/ directory.

The src/snippet.js file is what is compiled into the dist/snippet.html file. All of the other files in the src directory are compiled into the dist/openpixel.js and the minified dist/openpixel.min.js files.

Continuous integration

You may also need to build different versions of openpixel for different environments with custom options. Environment variables can be used to configure the build:


You can install openpixel as an npm module npm i -ED openpixel and use it from your bash or js code.

OPIX_DESTINATION_FOLDER=/home/ubuntu/app/dist OPIX_PIXEL_ENDPOINT=http://localhost:8000/pixel.gif OPIX_JS_ENDPOINT=http://localhost:800/pixel_script.js  OPIX_PIXEL_FUNC_NAME=track-function OPIX_VERSION=1 OPIX_HEADER_COMMENT="// My custom tracker\n" npx gulp --gulpfile ./node_modules/openpixel/gulpfile.js build

Tracking Data

Below is a table that has all of the keys, example values, and details on each value of information that is sent with each beacon on tracking pixel. A beacon might look something like this. Note: every key is always sent regardless of if it has a value so the structure will always be the same.;%20Intel%20Mac%20OS%20X%2010_11_5)%20AppleWebKit/537.36%20(KHTML,%20like%20Gecko)%20Chrome/50.0.2661.102%20Safari/537.36&utm_source=&utm_medium=&utm_term=&utm_content=&utm_campaign=
Key Value Details
id SJO12ZW id for the app/website you are tracking
uid 1-cwq4oelu-in95g8xy id of the user
ev pageload the event that is being triggered
ed {'somedata': 123} optional event data that can be passed in, string or json string
v 1 openpixel js version number
dl document location
rl referrer location
ts 1461175033655 timestamp in microseconds
de UTF-8 document encoding
sr 1680x1050 screen resolution
vp 1680x295 viewport
cd 24 color depth
dt Example Title document title
bn Chrome 50 browser name
md false mobile device
ua full user agent user agent
tz 240 timezone offset (minutes away from utc)
utm_source Campaign Source
utm_medium Campaign Medium
utm_term Campaign Term
utm_content Campaign Content
utm_campaign Campaign Name