What does market share mean here?
It's the share of sites we list that run a network. It says nothing about ad revenue or how much traffic each network serves. One big news site and one small blog count the same.
Many sites run more than one network, so the shares add up to more than 100%. A site counts once in sites listed, and once for each network it runs.
Google AdSense leads because it takes sites of any size. To compare managed networks, look past it to the ones below.
How do you read the other charts?
| Chart | What to keep in mind |
|---|---|
| Net change | A site counts as lost only after its network has ended, which takes three missed checks over seven days or more. A short gap doesn't move it. |
| Biggest switches | A switch is one main ad network replacing another within seven days. A site that adds a second network isn't a switch. |
| Sites of each size | Groups come from Chrome's list of the most visited sites. Not ranked means the site wasn't in that month's list, not that it has no visits. |
| Joining rule vs sites | Only networks with a public traffic minimum appear. Revenue rules, like Mediavine's, aren't on this chart. |
| Domain age | The middle age of each network's sites. Half are older and half are newer. |
| ads.txt files | Broken lines are lines that don't follow the ads.txt format. Ad systems skip them. |
Charts that need history, such as share over time, fill in as our daily counts build up. We don't invent past numbers.
What can't these numbers tell you?
- The whole market. We count only sites we've found and confirmed, across 44 networks. Networks that publish a full seller list are easier for us to find, so smaller networks without one may be undercounted.
- When a site joined. Our history starts with our first check of each site, in 2026. A network may have run there for years before that.
- Earnings or visits. We don't estimate either. There's no public source we can check them against.
- Sites that block us. If a site blocks our checks, we can't confirm it. Without a readable ads.txt file, we can confirm only the few networks we can spot from homepage ad code alone.
How do we collect this data?
Which networks a site runs comes from our own checks of its ads.txt file and, for some networks, its homepage ad code. A network's seller list only tells us which sites to check. The other facts come from the sources below. The ad networks directory explains what counts as confirmed and what we leave out.
| Data | Where it comes from | How often |
|---|---|---|
| New sites | Networks' public seller lists and official publisher lists | Weekly |
| Network checks | Each site's ads.txt file and homepage ad code | Every hour in batches; each confirmed site about once a week |
| Counts for the charts | A snapshot of every network's totals | Daily |
| ads.txt summary | Line counts, companies, and format errors from each file | Daily |
| Platform | Signs in the homepage code, such as WordPress | Daily, refreshed every 30 days |
| Domain age | The registration date in the registry's public RDAP record | Daily, for new sites |
| Traffic groups | Google's Chrome UX Report top-million list | Monthly |
| Niches | We sort each site into one of 20 niches | Weekly, for new sites |
A network moves to Not seen lately after two checks at least 48 hours apart miss it, and to Ended after three checks over seven days or more. A failed check, such as a timeout, never counts as missing.
Traffic groups use Chrome UX Report data from Google, under the CC BY 4.0 license.