An ad server plays an important role in digital advertising, but thanks to the abundance of programmatic tech like DSPs and SSPs, there's a lot of confusion around what exactly it does.
This article dives into what an ad server is, as well as lists the Top 10 Best Ad Servers.
An ad server is the ad technology that enables the management, serving, and tracking of an ad or internal promotion on one's digital properties. Ad servers decide, in real-time, the best ad to serve based on relevance, targeting, budgets, and revenue goals.
There are two types of ad servers: publisher-side (or, sell-side) and advertiser-side (or, buy-side). While similar tech is involved, the use cases are very different:
|Purpose||Serve and manage ads appearing on one's own digital properties||Easy creative management and tracking of one's ads as they appear on another publisher's website/apps|
|Used by||Sales, ad operations, or end-users (if it's a self-serve platform)||Marketers|
|Main value||Helps monetize one's digital properties; allows publishers to easily store and manage what ads appear on their site/app||Improves marketing paid spend performance through real-time creative optimizations and easy creative rotation; provides independent tracking metrics|
In general, third party ad serving vendors specialize in one or the other, although some brands do cater to both uses.
A publisher-side ad server is the tech that enables:
Also, as a point of clarification, if you are working with a programmatic partner (SSPs/DSPs/etc), then some of these steps are done by them, not by your ad server. But an ad server would manage all those pieces for direct-sold ads and internal promos.
There are multiple reasons to pursue an ad server:
This strategy is often used by eCommerce brands, whose vendors pay to be promoted in daily/weekly emails.
Yes! Let’s say I’m the owner of GoalTrackr, a tool for monitoring your spending habits.
My board is angry about our lack of subscription revenue growth, so I decide to supplement our income by selling ads inside our dashboard. I begin by chatting with banks, who would like to promote their credit cards.
I first contemplate whether I can just use our content management system (which manages everything else the user sees) to insert the ads into the dash. Unfortunately, in chats with the advertisers, it's clear they won't spend unless I offer:
This complexity is not something I can do with my CMS, so I realize I need ad server software.
And since I want native ads that won't ruin the user experience, I decide to build the ad server myself. Rather than spending a year on the project, I use third-party cloud tools such as Kevel to cut down my build time and launch in just a couple of weeks.
Once it's built, I upload my advertisers' creatives into the system, set up my targeting and business rules, and turn the campaigns on.
A CMS is the tech that manages digital content. This can be home-built or a hosted service like WordPress or Drupal. While content management systems and ad servers are alike in that they manage the display of content, as mentioned above, the big difference is that an ad server includes an ad decision engine.
For instance, if you only had one advertiser, and they were appearing in the same spot to everyone, you could of course just use a CMS to insert this.
The ad decision engine is the magic that makes this happen. It ingests business rules defined by the publisher (such as enabling 1st-price auctions to increase CPMs) and advertiser goals (such as $20K spread evenly over a month), and then, out of 100s or even 10000s of ads, it chooses the right one to show in just milliseconds.
Ad networks/exchanges/SSPs/DSPS are all components of programmatic advertising, a way for advertisers and publishers to buy and sell ads at scale without direct relationships.
Usually a publisher installs some code onto their site/app, which sends a call to a programmatic partner, who then returns an ad to show. The publisher then gets paid for showing these ads.
Indeed, it's possible to serve ads without using an ad server at all: just install an ad network's code onto your site and have them do all the work.
But if you wanted to manage direct-sold ads, in-house ads, and/or multiple programmatic vendors, you'll want an ad server.
Not at all! An ad server can be used to manage any type of digital ad:
It should be noted that if you are working with an off-the-shelf ad server, it's unlikely it can accommodate use cases outside of standard banners.
For native or custom solutions (like out-of-home ads, map ads, in-game ads, etc), you'll want to partner with someone that does server-side ad serving, or build it yourself.
Many large publishers - such as Google, Facebook, Pinterest, LinkedIn, Reddit, etc - built ad servers that they then turned into self-serve ad platforms, where advertisers can sign-up by themselves, set up campaigns, and get reporting on performance.
Ad servers can therefore be public-facing, as long as you want to invest in building out the front-end.
The exact features of an ad server will depend on the vendor you use or what you build.
There is no ad server out there that includes all of the features mentioned below, but most will employ a majority of them. This is just a sampling; we have a more exhaustive list here.
Also, as mentioned above, if your focus is programmatic demand, some of these features are managed on the network/exchange/DSP side, not by the ad server.
|Type of Targeting||Example|
|Zone/placement||Location on page; spot in search results|
|Frequency capping||Show same ad only once to a user per day|
|Keyword||Ad appears in the search results for ‘red hat’|
|Day & hour parting||Show ads just on Saturdays, 9am-5pm|
|City/DMA||Durham, NC only|
|Behavioral/interest||Shoe lovers (visitors who have searched for shoes in the past)|
|Ad pacing by time frame||Decision engine ensures a 30MM monthly impression goal is spready evenly across every day|
|Ad capping||A campaign gets paused after $500/day is spent, give or take just 1%|
|Goal optimizations||The advertiser bids via CPC but wants the system to optimize for a $20 cost per conversion|
|Priority waterfalls||Publishers can set rules so that premium direct sponsorships get priority placement, and if there's no ad to fill a spot, it'll move onto house ads|
|eCPM auctions||Rather than flat CPM or CPC pricing, the ad server picks the ad that will drive the most revenue for the publisher, using historical click-through-rates and current bids|
|2nd-price auction||A setting where the winning ad pays $0.01 more than what the 2nd-highest bidder bid|
|User interface||Hosted UI for campaign management, storing creatives, and reporting|
|Management APIs||APIs for programmatically creating/managing ads|
|Forecasting & sales reservation||For predicting future traffic and selling against that|
|Structured campaign hierarchy||Advertiser → Campaign → Ad Group → Ads|
|Campaign scheduling||Start on 9/15 and end on 10/15|
|Flexible ad unit options||So you can show 300x50 banners, native ads, email ads, out-of-home ads, etc|
|Macros||Tools that dynamically insert a user's location into the ad|
|Tracking & reporting||Impressions, clicks, conversions, and custom events by advertiser, campaign, ad, etc|
|Third-party tag enablement||Including advertiser-side ad servers and brand verification tags, like Moat|
|GDPR compliance||Consent prompt and back-end database to store info|
|User management (advertiser logins)||A system for creating user logins, scheduled reporting, etc|
|Multiple server locations||Servers in Seattle, Singapore, etc, to ensure the fastest response times|
Woah! That's a lot. And it's why trying to build an ad server from scratch (or trying to use your standard CMS) isn't going to be the most efficient path.
There are four main paths:
The pros and cons of each are:
A company with plenty of engineering resources could build an ad server themselves and host it on their servers.
|You can build exactly what you want, and there should be seamless integration with your organic content. You also don't have to rely on a third-party, who could change pricing or go under. It's this path that many successful publishers have taken: Google, Facebook, LinkedIn, Amazon, and so on.||It's going to be time-intensive and costly. Google and Facebook have 100s of ad tech engineers, for instance. You then have to maintain and continuously optimize the product. Trying to prioritize the project could also prove to be a hassle.|
|You can create a fully-customized ad server with all the bells and whistles you want while cutting down build time by 90%+.||It still requires engineering resources. Substantially less than if building from scratch, but this path isn't an out-of-the-box ad server.|
There are open source ad servers you can download for free or a nominal one-time fee. The scripts are then hosted on your servers and run by you.
|You get quick access to an ad server architecture without having to pay a monthly vendor fee or worry about sharing your data with anyone.||There's still engineering work needed to host the script. The tools are also not very customizable, and there's no support team for troubleshooting.|
Type: Ad serving Infrastructure APIs
Kevel is the market leader in server-side ad serving, enabled through APIs.
With Kevel, brands can launch custom, fully-bespoke ad servers in a fraction of the time and cost of trying to build it from scratch. Companies expecting to build an ad server in months or a year can use Kevel to easily release the same one in just weeks.
Type: Hosted third-party ad server
Of the popular ad servers, Google Ad Manager (previously DFP or DoubleClick for Publishers) is the leading third-party ad server by a wide margin, and it benefits from a seamless integration with Google's other ad products.
Type: Free, open source ad server
Revive Adserver, which spun out of OpenX many years ago, is a self-hosted ad server (via an open source script) you can download for free. After downloading, there is additional work needed to host and run the code. In 2019 they also released a hosted version.
Capterra: 4.2 stars
Type: Hosted third-party ad server for programmatic ads
Smart Ad Server is a Google Ad Manager competitor whose selling point is its integration with an SSP for instant access to programmatic demand. Additionally, they are pre-integrated with multiple brand safety vendors, DSPs, and DMPs.
Type: Hosted third-party ad server for programmatic ads
Like Smart, Adform is a GAM competitor who focuses on programmatic-focused publishers. Their platform comes with detailed revenue forecasting, analytics for identifying new monetization opportunities, and bidding tools to maximize CPMs.
G2Crowd: 4.5 stars
Type: Hosted third-party ad server for ad networks
EPOM is an ad server that caters to ad networks; their key value is around white-labeling and turnkey RTB integrations. They are also open to custom development.
Type: Hosted third-party ad server for digital magazines
Broadstreet provides a niche adserver to digital magazines and online news sites whose focus is on direct-sold ads.
G2Crowd: 4.9 stars
Type: Hosted third-party ad server for emails
While most ad servers offer email compatibility, email-only ad servers exist too, such as LiveIntent. LiveIntent acts as both an ad server and a network for monetizing emails. They also offer robust filtering options to personalize and optimize messaging.
G2Crowd: 3.5 stars
Type: Hosted third-party ad server for mobile apps
Most ad servers enable app targeting, but if you're looking for an app-specific mobile ad delivery platform, MoPub will be a great option. Bought by Twitter in 2013, they're the leading mobile app mediation solution for managing direct-sold and programmatic ads.
G2Crowd: 3.5 stars
Type: WordPress plug-in ad server
If you have a low-traffic WordPress site and GAM seems too complicated, the Ad Inserter WP Plug-in is a good option. It has the most active installations of any WP ad server solutions and provides an easy way to manage direct deals and Google AdSense ads.
Yup! Here's a quick highlight of which ad server is going to be best for you, based on your needs:
|Where are you getting demand?||Need a customizable ad server?||Where are you showing ads?||How do you define yourself?||Your best bet is:|
|Direct + programmatic||Yes||Websites, apps, emails, DOOH, in-game||You want a fully-customized ad server without the hassle of building it from scratch||Kevel|
|Programmatic||No||Websites, apps||Standard web publisher|
|Programmatic||No||Emails||Brand looking to monetize large email list||LiveIntent|
|Programmatic||No||Websites||Low-traffic WordPress site||Ad Inserter WP Plug-in|
|Programmatic||Yes||Websites, apps||An ad network, ad exchange, etc||EPOM|
|Programmatic + direct||No||Websites||You want a basic ad server, but don't want to build it or work with a vendor||Self-host with Revive|
|Programmatic + direct||No||Apps||An app developer who wants to manage direct sold and programmatic app ads||MoPub|
|Direct||No||Websites, apps||A digital magazine||Broadstreet|
The above brands constitute over 90% of the market, and it’s highly recommended you work with a leader. But if the above options aren’t interesting, below are some additional third-party ad servers, most being smaller brands with fewer than 15 employees.
Time has not been friendly to once-leading ad servers, so I wanted to point out some major ad servers that are no longer around. Indeed, if you were to look at a “Best Ad Server” blog from 2014, these would likely have been in the Top 5.
If you're still unsure of what to do next, we are more than happy to set up a 15-min consultation to walk through your needs and discuss the best path forward. We wish you the best in your quest to launch an ad server.
Chris has worked in ad tech for over fourteen years in a variety of roles - giving him customer support, PM, and marketing perspectives from both the advertiser and publisher sides. He's the VP of Marketing at Kevel.