What is an SSP?

What is an SSP? (As it relates to mobile apps)

SSP is an acronym for Supply Side Platform. It is a technology platform that allows app developers to sell their ad inventory at the highest possible rates. You may have heard of DSPs, or Demand Side Platforms, as there are a lot of them. DSPs are the technology platform that allows advertisers to more efficiently buy ads. In the middle is an exchange where the ads are actually traded. So in the simplest terms, SSPs allow app owners to sell programmatically and DSPs allow advertisers to buy programmatically.

There are hundreds of DSPs in existence and only a relative handful of SSPs. The reason for that is that the barrier to entry to become a DSP is pretty low. You can use off-the-shelf technology, get a seat on an exchange and you’re ready to go. Actually making money at it will be another matter, but getting in the game isn’t that hard compared to creating an SSP. An SSP needs to build a base of app developers that use their technology and to compete, an SSP needs a lot of functionality that truly works to hang on to those developers. Also, with no exceptions I can think of, SSPs also run the exchange. So there is a lot of technology that must be built to become a competitive SSP.

How does an SSP sell inventory?

Generally speaking, there’s a 3 step process to clearing an ad impression in an SSP. The first step is to see whether it can be sold directly. SSPs usually allow you to insert direct deals and flight them with a higher priority level than other inventory. That ad serving functionality is typically not as robust as a traditional ad server. The targeting options might be more limited and there’s usually no ability to forecast the future availability of inventory. However, unless you have several direct sales people on staff, those limitations shouldn’t come into play very often. The SSP checks an impression against any direct campaigns in the system and if it matches it will be cleared there, if not, it goes to step 2.

Step to is where the inventory is cleared on the exchange. You can easily set floor prices via your SSP so that impressions cannot be sold unless they are above a certain price. This allows programmatic buyers on the exchange to take a look at any inventory you don’t sell directly and determine what they’ll bid for it. If their bid is above your floor rate and/or above what step 3 offers, the impression will clear at this point.

The third step is ad network mediation. Often called a waterfall or a daisy chain, this is a process of offering the impression to a string of demand sources and decreasing rates until someone takes it. If no one wants the impression or if it takes too long in total to get the responses back, then the impression goes unfilled.

The execution of this process is much more complicated and not as linear as I’ve described it here. But any given impression is offered first to direct buyers and then to one or more exchanges and ad networks at various price points until it is sold (or not).

Ad Quality

That’s only one facet of what an SSP does. Another important aspect is allowing the app developer to control the quality of the ads users see on their apps. This is an area where the capabilities of SSPs vary more widely. It is possible to block ad campaigns or advertisers on any exchange. It’s also possible to block whole categories of advertisers, like those running ads for gambling. There are relatively few situations in which you can’t block the ads you want to remove in an exchange environment. The only issue is that you still have to monitor ad quality because bad ads will always get in one way or the other. If the impression gets to the ad network mediation level, then the problem gets harder. The SSP isn’t responsible for ads that come from the mediated networks, so if the bad ads originate there you have to track down the responsible network and block the ads within their system.


Another facet of what an SSP does is to provide reporting so that you can analyze and improve the performance of your ad monetization. The features will vary but the SSPs reporting on direct campaigns and anything that happens on the exchange should be quite good. Reporting on mediated ad networks is usually fraught with errors and discrepancies that have to be sorted out because different systems will always count things a little differently. I’ve worked with most SSPs in existence and have never seen any with rock solid network mediation reporting.


Above are the main characteristics of an SSP, though if you dig deeper there are many more complexities to uncover. If you want to dig a little deeper, the next article shows you how to choose an SSP that suits your product.​

Click Here to Leave a Comment Below

Leave a Reply: