OpenX is an open source advertising brokerage solution. US based vendor OpenX publishes and supports the tool. OpenX provides good control of advertising campaigns for one or more websites, along with data on campaign results.
OpenX enjoys a relatively vast functional scope, handling multiple sites and advertisers, schedule based banner displays (with start and end dates), rotating displays in a single zone, multiple formats (IAB and more), limits on the number of clicks or displays per day, management of priority campaigns, etc. OpenX supports a wide variety of media, such as images, HTML, JavaScript, Flash, Google Ad Sense, DoubleClick, Atlas and Yahoo!). Statistics can also be calculated by campaign, with tracking of displays, clicks and clicks by channel, reports exported in Excel, HTML or CSV format, etc.
OpenX is distributed under the GPL v2, but also under a commercial licence and as part of a SaaS package. Unfortunately, the open source version appears to have been somewhat abandoned in favour of the latter.
The application can handle hundreds of millions of impressions per month. It runs on an Apache (or HTTPd) web server with PHP, MySQL and a PHP accelerator.
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