What is an Open Source Ad Server? A 2022 Guide

In order to monetize your site or app, you'll first need an ad server, the tech required to serve and report on both direct-sold and programmatic ad spend.

In your search, you may come across the terms 'open source ad server' and 'hosted ad server'. But what do they mean, and when should you choose one over the other?

This article answers these questions while diving into the pros and cons of open source ad serving.

What is an open source ad server?

An open source ad server is an ad serving script that you download from a third-party and then host on your own servers. It's also called a self-hosted ad server.

While the code is usually free, it’s on you to maintain and run the service, and you will have to pay all server costs.

The leading solution here is Revive Ad Server, with smaller ones including OIO, dJax, and InOut. Due to the complexity of ad serving tech, few open source solutions exist, and there have been no new ones of note for years.

What is a hosted ad server?

A hosted ad server is ad serving tech managed by a third-party vendor. You get access to the service by subscribing to it, with costs usually related to traffic volume and/or a percentage of revenue.

With a hosted solution, the vendor does all the heavy lifting for you, like support, server costs, troubleshooting, maintenance, and the ilk.

For non-technical brands looking for a plug-and-play ad server, Google Ads Manager (previously, DoubleClick for Publishers) is the go-to solution.

For companies who want a more flexible and technical solution, the leading solution is Kevel, which provides APIs that make it easy for publishers to build custom ad products.

What are the differences between hosted and self-hosted solutions?

Below touches upon the major differences.

	Self-Hosted	Hosted
Pricing	Free, downloadable script	Varies - but generally based on traffic volume and revenue driven through the platform
Server Costs	You would need to pay for your own servers and volume	Included in fee
Maintenance Costs	You would need a dedicated internal team to set-up, maintain, and add new features	The hosted solution will maintain the product for you
Support	None	Usually comes with account managers and technical support teams
Code Flexibility	Code can be adjusted for your particular needs but is still limited to what features the script offers to begin with	You don't have access to the raw code. Any ad serving tech with ad serving APIs, though, can likely provide the flexibility to build what you want.
Uptime	As high as your tech team is able to keep it. Will involve monitoring load distribution, stopping DDoS attacks, and watching bandwidth usage	Most guarantee 99.9%+ as part of their contract
Bugs	You will need to troubleshoot and fix	The vendor will fix it for you
Data	No data is sent to a third-party	You would be sharing data with a third-party, although you could work with them to anonymize and minimize what is sent
Security	You will need to monitor and keep abreast of changing privacy laws, like GDPR and getting Privacy Shield Certified	Hosted solutions usually have built-in security protocols and privacy-law-compliance by default

Should I use an open source ad server?

Open source ad serving may look good on paper (they provide flexibility, there's no vendor costs, etc), but ad serving tech is not something that can be set up and forgotten; it needs constant monitoring to ensure everything is serving correctly.

Due to this, you should pursue open source only if you have the engineering resources to maintain the tech (based on your traffic volume, this could be one engineer to a large team).

Server costs can also add up. While hosted solutions can secure high-volume discounts from cloud providers, you may not be so lucky - leading to higher-than-expected monthly infrastructure bills.

Pricing, therefore, should not be viewed as the reason to use open source ad servers (you can read more about hidden ad serving costs here).

The main consideration, instead, should be around data. If your company policy (or personal preference) gives you zero ability to share even anonymized data with a third-party, then a hosted ad server is not a tenable solution.

Even then, open source ad servers are prone to security-issues and malware attacks - so you'll still need to weigh data leakage risks.

Hackers in 2020, for example, breached Revive’s software and inserted malware into at least sixty publishers and thousands of sites.

Are there other options?

Yes; in fact, viewing it as 'open source vs hosted' misses out on a path many successful businesses have taken: building in-house ad platforms from the bottom up.

Most companies who have the engineering resources to maintain an ad server end up just building their own from scratch, rather than using open source scripts.

This is what many large brands have done, including Etsy, Instacart, Pinterest, Facebook, and Amazon.

Building such an ad platform from scratch (or using ad serving APIs to cut down the build time) enables you to design the exact ad product you need, rather than relying on a potentially-imperfect open source solution.

This will come with more upfront build time, but once it's released, you'll have more control over the tech versus having to maintain code you didn't write yourself.

Currently the market leader for ad APIs is Kevel. If you're interested in a free consultation around how to build a custom ad server in just weeks, feel free to reach out!