A supply-side platform (SSP) helps publishers and app developers sell ad impressions to many buyers at once. The SSP packages each impression into a bid request, sends it to demand-side platforms and exchanges, runs or joins the auction, and pays the publisher. In 2026 most serious publishers use several SSPs at once — through header bidding on the web or mediation in apps — because more competition per impression means higher prices.
The major web SSPs
Google Ad Manager (AdX)
Combines an ad server with Google's ad exchange. For large, multi-format publishers it offers deep demand and direct-deal tools. It can be complex to configure, and relying on it alone creates dependency on one ecosystem.
Magnite
One of the largest independent SSPs, with strong video and CTV roots and broad display and mobile coverage.
PubMatic
An omnichannel SSP known for yield-optimisation tools and growing CTV reach.
Index Exchange
Often recommended for transparency and clean auctions, especially for publishers with premium inventory and direct deals.
OpenX
Known for demand quality and inventory controls.
Other options
Sovrn, Media.net, Equativ, TripleLift (native) and others serve mid-tier and specialist publishers or specific formats.
App monetisation: mediation platforms
App developers usually sell inventory through mediation platforms that run an auction among ad networks and bidders inside the app:
- AppLovin MAX
- Unity LevelPlay (formerly ironSource)
- Google AdMob
Each supports in-app bidding from many demand sources. As on the web, the best result usually comes from testing which networks add incremental revenue.
How header bidding fits in
Header bidding lets several SSPs bid on the same impression before the ad server decides, instead of passing the impression to them one by one. Prebid (open source) is the most common framework; Google's Open Bidding offers a server-side alternative. More bidders raise competition but add page latency, so publishers balance the number of partners against speed.
How to choose and test SSPs
| Criterion | What to look for |
|---|---|
| Demand quality | Unique buyers, not the same DSPs you already have |
| Formats | Display, video, native, CTV, in-app |
| Fees / take rate | Ask directly — rarely published |
| Payment terms | Net 30, 45, 60; minimum thresholds |
| Transparency | sellers.json listing, reporting depth |
| Controls | Floors, brand-safety blocks, advertiser blocks |
| Support | Account management and integration help |
Testing method: add one SSP at a time, compare net eCPM and fill rate after fees on the same pages over at least two weeks, and drop partners that do not add incremental revenue.
Hygiene that raises your revenue
- Keep ads.txt / app-ads.txt accurate — buyers skip unauthorised sellers.
- Make sure each SSP lists you correctly in sellers.json.
- Improve viewability — buyers pay more for ads that are seen.
- Block low-quality demand that hurts user experience.
- Collect consent properly where required, so buyers receive privacy signals.
Alternatives for smaller publishers
Smaller sites and apps often start with ad networks or managed partners that bundle several SSPs, or with smartlinks and CPA offers for specific traffic types. See what a smartlink is and our publisher programme.
FAQ
What is the difference between an SSP and an ad exchange?
An ad exchange is the marketplace where auctions happen. An SSP is the publisher's tool for managing inventory, floors and connections to exchanges and DSPs. Many SSPs operate their own exchange.
How many SSPs should a publisher use?
Enough to create real competition without slowing the page — many publishers run three to eight bidders through header bidding and test each one's incremental value.
What is a take rate?
The share of the advertiser's payment the SSP keeps as its fee. It varies by platform and deal and is usually negotiated.
Sources
- Publift — Best SSPs for publishers (opens in a new tab)
- Epom — Top SSP examples for publishers (opens in a new tab)
- IAB Tech Lab — ads.txt and sellers.json (opens in a new tab)
- Prebid.org (opens in a new tab)
Published 25 October 2026 by the ClickSpero Editorial Team. Platform features, fees and policies change often — check the provider’s current terms before you rely on a number. Third-party names are trademarks of their owners; no endorsement is implied.