How to Choose Ad Server in 2025: Pro Tips, Hidden Traps & Smart Picks

In digital advertising, results often depend on your willingness to try new things and constantly optimize performance. Still, even the best effort without strong software is like riding a bike with square wheels—slow, painful, and sometimes impossible. The right ad server can make your life easier, while the wrong leads to lost revenues and increased risks.

But how to choose ad server among multiple options in the market? Read our ad server guide to find out what factors you should consider as a publisher or an advertiser!

What Is an Ad Server?

The digital advertising ecosystem is like a superb orchestra: it consists of different elements, each playing a vital part. An ad server is an essential link. Like a conductor ensuring smooth music, an ad server guarantees a seamless experience for publishers, advertisers, and visitors.

To give you a formal definition, an ad server is a platform that manages, delivers, and tracks ads. All players need it: publishers, advertisers, ad networks, supply-side platforms (SSPs), and demand-side platforms (DSPs).

Let’s cut to the chase: an ad server ensures the advertiser’s ad reaches the right audience at the proper time and optimizes the campaign performance. For publishers, an ad server picks the highest-paying ad for every impression. One platform, gain for both sides!

How Does an Ad Server Work?

Despite an ad server being a bedrock for advertisers and publishers simultaneously, their perspectives differ. Let’s discuss the two sides of the ad delivery process in detail.

Publisher’s Angle

When a user visits a publisher’s website or app, the ad server receives the request to fill an ad slot. It starts to choose an ad to display. Often, there are several options:

• Directly sold ads (if the publisher has a direct deal with an advertiser).
• Private marketplace (PMP) deals.
• Ads from programmatic auctions using real-time bidding (RTB).
• Backfill ads (publisher’s own or coming from lower-priority ad networks).

Directly sold ads usually have the highest priority, so the ad server will display them if they are available. If not, it will move to the other options and use specific criteria to choose among them. These may include:

• Targeting criteria, such as demographics, user behavior, geolocation, the type of user’s device, etc.
• Frequency capping rules (for example, no more than three impressions per day for a user).
• Visibility rules (ads more likely to be seen have a higher priority).
• Brand safety (low-quality ads have lower priority).

After the ad server decides, it displays the ad on the publisher’s website or app. The whole process takes milliseconds and ensures an uninterrupted user experience.

Advertiser’s Angle

For advertisers, the process starts with uploading ads to the ad server and setting up targeting rules, bidding strategy, frequency capping rules, etc. When a user visits a publisher’s website or app, their ad server sends a request to an ad exchange, and the real-time auction starts.

The advertiser’s DPS decides whether this ad slot is worth bidding on, and if yes, it bids. In case of a win, the advertiser’s server delivers the ad to the publisher’s.

In both cases, the ad servers collect data that advertisers and publishers can later use to optimize their strategies.

Ad Server Examples

By now, you must be wondering if all ad servers suit both publishers and advertisers. The answer is no. Some focus primarily on publishers (one of the most popular examples is Google Ad Manager), and others mainly on advertisers (such as Google Campaign Manager 360).

Over the last few years, more and more ad servers have started offering features for both parties. For instance, Equativ (formerly Smart AdServer) initially focused on publishers but later added functionality for advertisers, as well as SSP and DSP features.

Other ad server examples include Kevel, OpenX, and Epom Ad Server. All of them are suitable for first- and third-parties (publishers and advertisers). Moreover, Epom offers a white-label solution that companies can easily customize to match their preferences.

Choosing the perfect ad server among dozens of options can be exhausting. That’s why we’ve created an ad server guide with a list of factors for publishers and advertisers to consider. Let’s explore them right now!

How to Choose Ad Server: Publisher’s Perspective

Finding the best ad server for your needs requires a thorough investigation. Here are some non-obvious but beneficial criteria for choosing an ad server.

Integration of Programmatic, PMP, and Direct Deals

Combining the power of programmatic advertising with the exclusivity of direct deals allows publishers to increase fill rates and maximize revenues. Plus, it’s convenient to have them both under the same roof. So, when analyzing potential ad servers, find out if they support programmatic auctions, private marketplaces, and direct deals.

Your ideal ad server must also provide dynamic allocation. Traditionally, ad servers prioritize direct deals, but this approach doesn’t guarantee the highest revenue since programmatic bids may sometimes be higher. Dynamic allocation ensures “fair competition”: the highest-paying ad is displayed.

Ad Load Speed

Maximizing revenues must include a long-term perspective. If a publisher’s website displays the highest-bidding but slowly-loading ads, eventually, this will harm the business. Such ads irritate visitors and can lower the website’s SEO ranking. To avoid this scenario, check every ad server option for delivery speed.

What’s more, find out if an ad server supports asynchronous ad loading. Usually, the website loads ads before the main content (synchronous loading). Asynchronous loading allows visitors to see the content even if ads require more time or don’t appear.

Ad Quality Control

Quite often, publishers don’t know the buyers of their ad inventory. Even if it comes with higher revenue, a shady deal can hurt the brand's reputation. What if an ad turns out to be intrusive or low-quality?

So, before committing to any ad server, we recommend asking: does it allow you to block specific advertisers and filter low-quality ads? Can you monitor bidding data? Will you know who has bought your ad slots? Positive answers to these questions add points to this ad server option.

Cross-Device Work

Today, consistent user experience is a must—and the same applies to advertising. Publishers want their ad servers to track performance on all devices, as users can see ads on their mobile phones, desktops, CTVs, etc.

So, explore your options with these questions in mind. Does an ad server support CTV, OTT, and DOOH ads? Does it track users across all their devices? Does it provide data over all devices in one report, saving you time on analysis?

Leveraging First-Party Data

Due to GDPR and CCPA regulations, cookies are gradually disappearing. Now, publishers need to collect first-party data directly from users, so an ad server must provide extensive functionality to leverage this information.

So, check if your future ad server offers first-party ID solutions, such as the open-source Unified ID 2.0 developed by The Trade Desk. Google Ad Manager has its own solution, Publisher Provided Identifiers, but it works only inside the Google ecosystem.

Comprehensive Reporting Features

When choosing an ad server, you can count on tracking basic metrics (like clicks and impressions), no matter what option you opt for. However, to maximize your revenues, you’ll need more.

Here are some features to consider: data segmentation (by geolocation, devices, etc.), access to real-time and log-level data. Also, it’s nice to have access to bid-level data so you can monitor advertisers’ bids and analyze their reasons. Some ad servers even allow publishers to create customized dashboards. It’s a convenient feature if you want to track a specific set of metrics connected to your goal.

The listed criteria help you find an answer to the question: how to choose ad server that perfectly matches the publisher’s needs. In the next part of our ad server guide, we’ll look at the advertiser’s side.

How to Choose Ad Server: Advertiser’s Perspective

Advertisers use different criteria for choosing an ad server because they want their ads not only delivered correctly but also optimized for performance. Here are some things they should consider when exploring options.

Ad Creative Management

Many ad servers offer various ad formats (such as banners, native, video, CTV), but you should compare what they offer to your preferences. So, ask yourself: what ad formats do we use the most? What are the formats we’d like to try in the future?

Then, find out if an ad server loads ads fast and can adapt them to different devices. Also, valuable features include bulk upload and management, creative rotation, and A/B testing.

Bulk upload is handy when you launch massive ad campaigns. This feature allows you to upload multiple ad creatives simultaneously, saving time and effort. Creative rotation helps fight ad fatigue by showing different visuals based on specific rules (for instance, rotation can be random or depend on performance). A/B testing allows advertisers to launch several versions of the same ad and compare their metrics. If an ad server has all these functions, it’s a solid option.

Another feature worth mentioning is dynamic creative optimization. If an ad server allows you to adjust ads on the go based on user behavior or other factors, you can achieve better campaign results.

Serving Ads Across Various Channels and Devices

Since your audience watches ads on different devices, your ad server must track campaign metrics, such as engagement, everywhere. Also, the best ad servers can retarget users on all devices. Finally, the valuable feature is cross-channel attribution. It helps analyze the effect of various devices on conversion rates.

Advances Targeting Options

Precise targeting is essential for campaign optimization, so your ad server should offer multiple essential targeting options, such as geotargeting, demographics, user behavior, device type, and advanced options, such as contextual targeting. This type of targeting focuses on the website content instead of other factors and matches ads with it.

Another interesting feature is lookalike modeling. It allows you to find users similar to the current audience based on specific criteria.

Fraud Detection

Great ad servers have built-in fraud detection tools, which saves advertisers a lot of money. So, you should determine if your future ad server can detect bot clicks and invalid traffic and allow you to block unreliable ad inventory.

Integration Capabilities

Advertisers often use several adtech services, such as DSPs, analytics, and tracking tools. Before signing up for an ad server, you should explore if it can integrate software you use seamlessly. If you plan to use custom API integrations, ensure an ad server allows it, too.

Real-Time Insights

For many advertisers, getting reports daily or even hourly is too slow. They need real-time data to optimize their campaigns and save the budget. If you prefer real-time reporting too, check ad servers for this feature.

Then, explore the platform's in-depth analytical capabilities. For example, does it provide the export of log-level data and granular reporting? Traditional reports contain summarized information, such as total impressions.

In contrast, granular reports break down the data and show various metrics, like where your ad was displayed, who saw it, and on what device. Such comprehensive reporting helps advertisers optimize campaigns in real time. Now, advertisers also know how to choose ad server and what to check during the screening process. The more precise you are at this stage, the better results you can expect when using the platform.

Watch Out! Ad Servers Reg Flags

Our ad server guide wouldn’t be complete without mentioning warning signs you may encounter. Ignoring them can cost you money and, sometimes, even brand reputation.

Non-Transparent Pricing

Hidden fees may result in overspending the budget. For example, some ad servers can charge you for third-party integrations or reporting. If you can’t find information about all the possible fees or a platform charges you a percentage of your revenue, it’s an alarming signal. You must look for an ad server with a transparent pricing model that is easy to understand and use.

Limited Integration Potential

If an ad server connects only to a few SSPs and DSPs, it should alarm you. After all, the more demand sources you can integrate, the higher your revenue. Therefore, make sure your ad server isn’t locked into just one ad exchange and supports multiple SSPs and DSPs. Bonus points for custom API support, if you need this feature.

Zero Control Over Brand Safety

If an ad server doesn’t have embedded fraud prevention tools, provides no control over ad quality, or doesn’t allow you to block sources, it’s not a valid choice. You need an ad server to protect you against malware ads, bot traffic, and invalid clicks. Don't settle for less.

Insufficient Customer Support

If an ad server’s support takes many hours or even days to answer, you’ll lose a part of your revenue. Ideally, your ad server should provide 24/7 customer support and resolve critical issues within one hour.

These red flags are too dangerous to overlook. So, if you remember only a single part of this article, let it be the one.

Pitfall-Free Checklist

To summarize the main points of our ad server guide, we’ve prepared a checklist. It will help you avoid common missteps when choosing an ad server. Before making a decision, ask yourself:

• Does this ad server support multiple ad formats?
• Does it integrate with multiple SSPs, DSPs, ad exchanges, etc.?
• Does it support asynchronous ad loading or other speed-increasing technologies?
• Does it have built-in fraud detection and brand safety tools?
• Does it support first-party data instead of being dependent on third-party cookies?
• Does it offer cross-channel and cross-device ad delivery?
• Is the pricing model fully transparent, with no hidden fees?
• Does it provide in-depth reporting?
• Does it have adequate and fast customer support?
• Does it have a “room to grow” (will it satisfy your needs if your business grows)?

The option with mostly positive answers can be a solid choice, and you can give it a try. Many ad servers offer a trial period that lets you comprehend if this is the right fit. One of them is Epom Ad Server — you can test its advanced features for 14 days free of charge.

FAQ

• What is an ad server?
  An ad server is a platform that manages, delivers, and tracks ads. It ensures the advertiser’s ad reaches the right audience at the proper time and optimizes the campaign performance. For publishers, an ad server delivers the most profitable ad.
• What is the difference between an ad network and an ad server?
  An ad server is a platform that stores, delivers, and tracks ads, helping publishers manage their inventory and advertisers optimize their campaigns. An ad network aggregates ad inventory from various publishers and sells it to advertisers.
• What is an example of an ad server?
  Some ad servers are focused primarily on publishers (like Google Ad Manager), and others mainly on advertisers (such as Google Campaign Manager 360). There are also ad servers suitable for first- and third-parties, such as Kevel, OpenX, and Epom Ad Server.
• How do I choose the best ad server to monetize gambling platforms?
  First, determine if an ad server supports programmatic auctions, private marketplaces, and direct deals. Also, ensure it provides dynamic allocation, always displaying the highest-paying ad. Then, consider factors like ad quality control, cross-device work, and advanced reporting.
• How to choose the best ad server for my online business?
  Find out if an ad server offers various ad formats (such as banners, native, video, CTV). Then, find out if an ad server loads ads fast and can adapt them to different devices. Also, your ad server should offer multiple essential targeting options, such as geotargeting, demographics, user behavior, device type, and advanced options, such as contextual targeting. Moreover, check if an ad server has fraud detection tools, can integrate with other adtech solutions, and provides real-time data.