Google's AdMob is surely the most common source of ads for monetizing your apps. This makes it the safe choice as well. If you are old enough, you may remember the saying, "No one ever got fired for buying IBM." The same philosophy could apply to choosing AdMob.

But what if you don't want to use the standard solution? Perhaps you are looking for higher payouts. Or maybe you couldn't get accepted into the AdMob program. Whatever the reason, if you want to try a different network, there are lots of options out there. Here are some alternatives to Google's AdMob (listed in alphabetical order) that you might want to investigate further:

Airpush

InMobi

LeadBolt

MobFox Publisher Platform

MoPub

RevMob

Smaato

Tapjoy

Unity Ads

Just to be clear, these AdMob alternatives were not chosen to exactly replicate AdMob's features and benefits. Each has its own unique slant on mobile advertising. This variety is great, since it increases the chances that there's a network that is ideal for your particular app and target audience.

Airpush is a mobile ad network with some unique, patent-pending technology. Their 360 Banner system can display Video Banners and IAB Standard Banners. It also supports their Abstract Banners system – transparent/translucent banners that display over the content, eliminating banner blindness.

360 Interstitials (formerly called SmartWall) allows your app to display Rich Media, Video, Dialog Ads, Airpush's AppWall, and other ad formats. As you can see in the figure that follows, the ads are placed on top of app content, right where the user's eyes are focused. The type of ad is automatically optimized to give you the best results.

Developers using Airpush get access to a portal that provides:

Near real-time traffic and earning stats

Audience segmentation analytics

Revenue and engagement analytics

Campaign controls

The Airpush SDK supports iOS and Android apps.

The InMobi network allows you to monetize your app with a wide range of ad formats. You can use direct or programmatically determined ads in these formats:

Mobile Video – HD ads in skippable, non-skippable, full-screen, pre-roll, vertical, and native formats

Native – Non-intrusive, contextual

Carousel – scrollable collections of related apps and products

Rich Media – MRAID compliant ads that have access to device hardware

Full-screen Interstitials

Behind the scenes, InMobi uses targeting techniques like Adaptive Lookalike, Appographic, and Geo-Context Targeting to give you the best results. They also support retargeting to help you maximize the revenue you earn from each customer.

The InMobi SDK is available for both iOS and Android. SDK documentation is available in English, Chinese, Japanese, and Korean.

With the LeadBolt Mobile Advertising network, you get connected to a range of top in-app advertisers and access to special limited release ad campaigns. Their Direct Deals Marketplace lets you search for and apply to the offers you like or their self-optimizing partner matching system can select offers for you. They also give you access to a dedicated monetization specialist.

LeadBoltr ad formats include:

Video Ads – Run ads from partners you meet in the Direct Deals Marketplace or try their Rewarded Video ads which they claim can boost your revenue by up to 70%

Interstitial Ads – Targeted, full-screen ads

Native Ads

To help you engage your users, LeadBolt offers a set of free developer tools. They give you mobile analytics (event tracking, install attribution, and crash analytics), quick-start guides, and framework support.

The LeadBolt SDK provides detailed instructions for working with more than a dozen frameworks, and is available for iOS and Android.

The MobFox Publisher Platform is used in over 40,000 iOS and Android apps. In addition, they support any app that can display Mobile Web ads. Their ad formats include Image banners, Full Screen Interstitials, HTML Markup ads and MRAID Rich Media. You get a range of targeting options and near real-time performance reports.

Another powerful feature is the MobFox RTB Exchange. Whenever your app requests an ad, the RTB (Real-Time Bidding) system finds the campaign that earns you the most from across multiple ad networks, automatically.

Supporting the RTB system, the MobFox Publisher Platform is integrated with 31+ mobile ad networks. With networks like InMobi, ONE Mobile, and Vserv, integrated, your app will have access to a huge range of advertisers. At the same time, MobFox gives you full control of the process so you can block unacceptable ads or set floor prices.

MobFox SDKs for iOS and Android are available on GitHub.

MoPub says they are, "...the world's leading ad server for mobile application publishers, designed to drive more ad revenue through a single solution." Their platform combines ad serving, ad network mediation, and RTB. The ad types they support include:

Image, text, tile, and HTML

Banner, Full Screen Interstitial, Native, and Custom formats

MRAID 1.0 and 2.0 for certified vendors

Beyond that, the platform offers a full set of capabilities for: campaign management, budgeting, targeting, and reporting, with greater than 99.9% server uptime.

The MoPub SDKs for iOS and Android are available on GitHub, as are detailed integration instructions for the SDKs and for Mobile Web applications.

Smaato is designed to be, "...a one-stop-shop for mobile app monetization." We're of course interested in the publisher side of their operation, where they do a lot of interesting stuff. One example is their Dynamic Demand model for filling ad requests. Without getting deep into the details, it is a system that tries to ensure that high-paying but low-fill-rate ad networks don't cause committed RTB bids to be ignored.

Another example is their SDK Mediation system. With it, you can bring in other ad networks at the SDK level to compete in Smaato's ad auctions. Some of the additional networks you can support this way include: iAd, MoPub, and AdMob

Smaato offers 4 SDKs: iOS, Android, Windows Phone, and Blackberry. The Android and iOS SDKs include SDK Mediation and are MRAID 2.0 compatible.

Tapjoy, Inc. makes a bold claim on their website:

"Every mobile app is leaving money on the table. Only Tapjoy's Mobile Marketing Automation Platform lets you optimize revenue from every user."

They claim that most apps only monetize 5% of their users. They have a predictive analytics system that identifies users who will and won't spend, and target those who will. Their rewarded ads are meant to generate revenue from the 95% that apps usually miss. Their approach to monetizing apps has three parts:

Acquire – Help developers target the best user segments and design app marketing to reach them

Analyze – Cohort analytics, future value mapping, IAP revenue, retention, and several more

Act – Use Tapjoy's analytics to segment your audience, push notifications to them, serve them reward ads and direct play video, and more

Tapjoy publishes iOS and Android SDKs, along with Unity, Adobe AIR, and Cocos 2d-x plugins. There's an integration guide for these included in the Tapjoy Dashboard.

One of the biggest challenges to gaining revenue from ads is getting your users to pay attention to them. We're surrounded by so many ads that most people have learned to simply ignore them. Unity Ads attacks this problem head-on with their rewarded video ads. The idea is to make the ads into something that enhances their experience, rather than being an annoyance they must sit through.

With Unity Ads, you offer your players in-game rewards for watching short video ads. For example, you can offer game currency, extra lives, new levels, score boosts, and so on. Unity says their ads provide, "...the highest ARPU of any global rewarded video as network."

If you are developing with the Unity Engine, you can start using Unity Ads simply by flipping a switch. If you're not using the Unity Engine, the Unity Ads SDK allows you to add the same ad technology to your app in just a few minutes.

The Unity Ads SDK supports iOS and Android apps. To help you get up and running, Unity provides a large knowledge base and an account support team.

Conclusion

As we've just seen, while Google's AdMob is the 10,000 pound gorilla in mobile ads for apps, there are lots of alternatives. If you want to move on from the standard way things are done, the nine ad servers covered here are good places to start your search.

That said, we've only scratched the surface here. While researching this article I quickly found more than 3 dozen ad servers. If there's another company that you think is superior to these, or you simply want to give your own thoughts on one of the nine I've covered here, please leave a comment.