Best Ad Servers for Publishers in 2021

April 19, 2021

Monetizing web content is one of the primary ways digital publishers can generate revenue. In 2019 digital advertising spending worldwide reached $333 billion, $50 billion up from 2018, and it only continues to grow. 

With so much expenditure at play in the advertising ecosystem, monetizing a site via ad campaigns is far more complex than just placing an ad and letting it run. Digital advertising campaigns require maintenance, management, testing, and editing to ensure continual improvement and maximum ROI.

This is where ad servers come to the party. They allow publishers and advertisers to manage ad space for multiple sites from a central console.

What Is an Ad Server?

An ad server is advertising software hosted on a server, used by publishers, web admins, ad agencies, and ad networks to facilitate and manage online ad campaigns. An ad server dictates what ad to display, at what time, and on what website or application. In this way, they can selectively display ads to site visitors based on pre-defined criteria.

Ad servers also can provide comprehensive reporting on campaign analytics and generate statistical reports (number of impressions, clicks, CTR ratio) that provide niche publishers with the ability to track advertising performance to better target their audience.

What Are the Types of Ad Server Platforms?

There are two predominant types of ad server platforms: hosted and self-hosted. Hosted ad servers are maintained and run by an ad server company, while self-hosted platforms are installed and maintained by the user.

What Is the Role of an Ad Server?

Advertising servers are platforms that serve ads. In a traditional ad serving workflow, around 40 different steps are required for an ad to be placed on a publisher's website, from selecting the publisher to directing the ad, to measuring the campaign's performance.

Traditional Ad Server Workflow Chart

For ad networks dealing with multiple publishers and ad campaigns, this can become extremely time-consuming and inefficient. This is where ad servers become invaluable for advertisers and publishers alike.

An ad server's role is to help advertisers efficiently run multiple campaigns across multiple formats from a central platform.

Ad servers give ad networks and advertisers the ability to:

  • Centralize their workflow for operational efficiencies
  • Own and make the most out of their ads' data
  • Report and measure the right insights

How does an Ad Server Work?

History of Ad Servers

To understand how an ad server functions, it is essential to understand why they came to be in the first place. When the internet began to gain popularity and functionality in the 1990s, traditional publishing methods began to move online. As online content grew exponentially, so did the advertising industry's opportunities to display ads in a digital format. 

Initially, online advertising was a fairly rudimentary process with a direct, manual exchange between publishers and advertisers. As the digital advertising ecosystem grew, publishers soon realized they needed to create advertising solutions that offered a more streamlined way to manage advertiser campaigns. From this need was born the original first-party ad server.

Ad serving platforms have since evolved dramatically. However, all ad servers operate similarly:

  • Firstly, a user opens a browser and navigates to a website or opens a mobile app.
  • An ad request featuring specific criteria is then sent to the ad server. These criteria may include the ad's dimensions, the geolocation, and the user device operating, amongst other factors.
  • The Ad Server consequently selects which ads are appropriate based on the above criteria.
  • The selected ads are then returned to the website or mobile app for display.
  • Finally, the Ad Server tracks the ad impressions and click-through rate (CTR) and stores this ad campaign data on the publisher ad server.

First-Party vs. Third-Party Ad Servers

Ad servers can be divided into two categories: first-party ad servers, and third-party ad servers.

What is a First-Party Ad Server?

First-party ad servers offer the following characteristics:

  • First-party ad servers are primarily used by a publisher's ads department to manage an advertiser's campaigns on the publisher's website.
  • First-party ad servers simplify the process of managing ads for publishers, allowing them to sell ad slots to advertisers directly.
  • They also have the ability to decide what creative assets should be displayed in a particular ad slot if no pre-defined campaign is running.

What is a Third-Party Ad Server?

Conversely, third-party ad servers are:

  • Primarily utilized by advertisers and agencies, third-party servers act to store and manage ad codes and deliver, track and analyze campaign results.
  • Verifies metrics such as ad impressions and CTR from campaign data are provided by publishers.
  • Third-party ad servers also facilitate A/B testing on ad campaigns for advertisers to refine and optimize creative output.

Hosted vs. Self Hosted Ad Servers 

Besides first-and third-party platforms, types of ad servers can be further defined as hosted and self-hosted.

Both hosted and self-hosted ad servers have their pros and cons, with each offering a different user interface and range of monetization options. Publishers and advertisers often have unique and individual needs for the ad serving process and should make an informed decision on which ad serving platform to use based on their specific requirements.

Here are some pros and cons of hosted and self-hosted ad servers.

Hosted Ad Servers


Ease of Use

Hosted servers are relatively easy to use, with little technical knowledge required by publishers.

No Installation

A hosted ad server requires no installation. Once publishers up to the service, everything is installed for them.


Similarly, all updates are automatically installed for the user once they are available.


Hosted servers offer a high level of user support.

Speed and Reliability

A hosted ad server is generally closely monitored by the provider to ensure speed and reliability.



Advertising utilizing a hosted server tends to run at a much higher cost than the alternative.


Tend to offer advertisers very few options for ad customization.

Data Control

Data is stored by the hosted ad server and therefore is not entirely under the publisher's control.

Self Hosted Ad Servers



A self-hosted ad server is fully customizable across the back and front end.


The cost of a self-hosted ad script is a one-time fee, with the only ongoing charge being the ad server’s cost.

Data Control

Another pro of an ad server that is self-hosted is that it offers complete control over the ads' data and reporting.



Advertisers need to install self-hosted scripts on the server themselves, which can require a certain level of technical savvy.


Publishers need to install updates as they become available - this does not happen automatically.

Technical Issues

Any technical issues need to be handled by the publisher without any support from the provider.

Open Source Ad Servers

Open-source ad servers are very similar to third-party ad servers. They provide similar functionality, including the ability to serve ads on websites and in apps and collect data for impressions, clicks, and conversions- all with the added benefit of being free for the advertisers' use.

How to Choose the Right Ad Server

As the digital advertising industry continues to evolve, players in the online advertising space must understand how to choose the appropriate ad server for their business.

Publishers and advertisers have fundamentally different requirements for what they need from an ad serving platform.


When it comes to ad serving, publishers need advanced control over ad elements such as ad inventory, ad formats, targeting, and campaign pacing, with tools to optimize creative delivery across multiple connected devices.

Publishers need the capability to track ad performance through their chosen platform to predict future inventory requirements.


On the other hand, advertisers require ad server platforms that are tailored to inform creative and campaign performance. Advertisers should look to choose an ad server that tracks ad impressions for individual ad units to ultimately optimize and inform the creative elements of future ad campaigns.

In general, publishers should use a first-party ad server to send ad codes to their website, while a third-party ad server will be more suitable for advertisers' requirements.

Best Ad Servers for Publishers 

Keeping the above niche requirements in mind, here are the top-rated ad servers for publishers and advertisers in 2021.

Hosted Ad Servers

  1. Kevel (previously Adzerk)

Kevel Ad Server Logo

Kevel is a suite of APIs that allows programmers to design, build, and launch a fully customized, server-side ad server in a matter of weeks. Kevel provides the functionality to run sponsored listings, internal promotions, native ad slots, and more. Plans start at $3K per month, and they are a trusted brand with clients such as Ticketmaster, Yelp, Strava, and Mozilla.

  1. DoubleClick for Publishers (DFP) (Now Google Ad Manager)

DoubleClick for Publishers

Previously known as DART for publishers, Google purchased this platform in 2008 and renamed it DoubleClick for Publishers (DFP), recently rebranding as Google Ad Manager

With numerous features, including an intuitive user interface, simple reporting and management tools, a range of monetization options, all backed up by the reliability of the Google network, Google Ad Manager is the ad platform of choice for many premium publishers. 

Furthermore, Ad Manager offers two versions of the server, including a small business version which is entirely free to use for publishers who are just getting their websites up and running.

  1. OpenX

A suitable option for larger publishers serving numerous ads monthly, OpenX is one of the most long-standing, reputable platforms. Despite its cost being on the higher side, OpenX offers publishers the ability to micro-target audiences and customize campaign reporting, with access to 12 months of historical analytics data. OpenX clients include CBS Interactive, Electronic Arts, and Samsung, to name just a few.

  1. Broadstreet
Broadstreet Ad Logo

The Broadstreet advertising server was initially designed for the ad serving needs of local news and magazine sites. The Broadstreet ad server offers a simple user interface and is intended to be accessible for users with little technical knowledge. They also provide prompt and knowledgeable technical support. Including integration with WordPress and email newsletters, Broadstreet is reasonably priced, making it an ideal ad serving platform for SMEs.

Self-Hosted Ad Servers

  1. DoubleClick Campaign Manager (DCM)
Double Click Campaign Manager Logo

DoubleClick Campaign Manager (DCM) - also known as Campaign Manager 360 - is one of the most widely adopted buy-side servers for advertisers and ad agencies. Offering an easy-to-use interface, DCM allows users to launch new ad campaigns within mere minutes and to make updates in real-time. DCM serves to centralize and streamline the ad-serving process.

  1. Revive Adserver
Revive Ad Server Logo

Revive Adserver is a free, open-source ad-serving script. While it has a long history, including several name changes and ongoing issues with bugs, it is still one of the most popular open-source ad server options for advertisers. This is primarily due to its extensive targeting capabilities, detailed reporting, including click-through rates, conversion rates, revenue, and eCPM, and the fact that it remains 100% free.

  1. Sizmek
Sizmek Logo

Sizmek is the world's largest third-party ad server and is aimed predominantly at professional marketers. Over the last 15 years, Sizmek has become a digital advertising space leader, including video ads and multi-channel online targeted advertising.

Sizmek offers a high level of creative control, multiple users’ ability to collaborate, and 24/7 technical support.

  1. OIO Publisher

OIO Publisher is a popular PHP ad management script that allows users to sell and serve ads on any website. This script can be installed as a standalone program or directly installed as a WordPress plugin. At $47, it is value for money and suits small, technically literate publishers.

For advertisers and publishers operating in the digital ecosystem, finding the right ad serving platform involves evaluating several factors. Understanding where your brand sits in the market, your financial assets, and what capabilities your company needs from its ad platforms will all help inform which ad server is right for your business.

At Publift, we help publishers navigate the ad tech landscape to get the most out of the ads on their websites. Contact our experienced team today to get started.

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