The definitive ranking of SSPs by the number of publishers listing them in their ads.txt file. Based on Red Volcano's weekly crawl of 32M+ publisher websites.
Methodology: SSPs ranked by unique publisher domains listing them in ads.txt. Data from Red Volcano's weekly crawl of 32M+ websites. Rankings reflect the most recent complete crawl cycle.
Pubmatic dominates with 37,994 publishers, followed by Rubiconproject (26,277) and Freestar (15,248). The gap between #1 and #10 is significant: Pubmatic has 9.8x more publishers than #10 (Infolinks).
| Rank | SSP | Publishers (ads.txt) | sellers.json Entries | Direct Sellers | Domain |
|---|---|---|---|---|---|
| 1 | Pubmatic | 37,994 | 6,241 | 3,290 | pubmatic.com |
| 2 | Rubiconproject | 26,277 | 3,245 | 1,481 | rubiconproject.com |
| 3 | Freestar | 15,248 | 775 | 774 | freestar.com |
| 4 | Sonobi | 11,462 | 418 | 223 | sonobi.com |
| 5 | Smaato | 10,698 | 3,194 | 1,488 | smaato.com |
| 6 | Sharethrough | 9,161 | 5,033 | 2,664 | sharethrough.com |
| 7 | Openx | 7,292 | 10,843 | 2,805 | openx.com |
| 8 | Aniview | 7,012 | 2,909 | 2,624 | aniview.com |
| 9 | Taboola | 6,924 | 19,594 | 18,256 | taboola.com |
| 10 | Infolinks | 3,887 | 931 | 906 | infolinks.com |
Red Volcano provides full SSP profiles including publisher networks, sellers.json transparency analysis, geographic reach, and competitive benchmarking.
Red Volcano scans ads.txt files across 32M+ publisher websites weekly. SSPs are ranked by the number of unique publishers that include them in their ads.txt file, indicating an active monetization partnership.
Based on Red Volcano's data, Pubmatic leads with 37,994 publishers listing it in their ads.txt. This makes it the most widely adopted SSP by publisher count.
The number of publishers listing an SSP in their ads.txt file is a proxy for the SSP's reach and adoption. More publisher relationships generally means more supply, more diverse inventory, and a larger marketplace.
Red Volcano refreshes all ads.txt data weekly. This ranking page is updated quarterly to reflect the latest data.